Consider the following: your grandfather has a cognitive disorder that prevents him from making connections between different experiences. He cannot, for instance, connect his past experience of you coming to visit last Tuesday with his current experience of you visiting this Tuesday. He always asks, “What day will you come visit next time?” You reply, “I’m off on Tuesdays, that’s why I’ve always come then. I’ll come back next Tuesday.”
Your grandfather also struggles with cause and effect. He doesn’t understand why your car arrives in his driveway every time you come to visit. He looks outside and asks, “What is your car doing here?” You respond kindly, “Well, I couldn’t teleport! I had to use the car to get here, so I parked it in your driveway.”
Is something wrong with your grandfather? We sure think so. It seems obvious that he should make connections between the past and the future. But in this reading, we will see some reasons to think that maybe you’re the crazy one after all… Let’s find out what David Hume would say!
A leader of the 18th century Scottish Enlightenment, David Hume is still one of the most famous philosophers, and one of few philosophers never to hold an academic job. In his day, Hume was derided as a skeptic and an atheist, but his works significantly influenced other well-known thinkers, including philosophers such as Adam Smith and Immanuel Kant and scientists such as Charles Darwin.
In this article, we’ll focus on Hume’s epistemology, specifically his criticism of the scientific reasoning that had been defined and used by Isaac Newton. In both Hume’s Treatise of Human Nature and An Enquiry Concerning Human Understanding, we find arguments that seem to support a skepticism about, or unwillingness to accept, the everyday beliefs we form about the world around us. In much of his Enquiry, Hume is concerned about the sort of reasoning that allows us to draw conclusions about things we have not directly perceived—what we might call induction. Let’s take a detailed look at Hume’s criticism of induction in a subsection of the Enquiry to find out what sorts of beliefs he calls into question.
Human Reason – the faculties/operations of the mind that allow us to draw conclusions from existing information. Hume takes there to be two sorts—demonstrative reasoning, which generates conclusions we can be certain of, and probabilistic reasoning, which suggests conclusions or shows them to be likely without guaranteeing that they are true.
Induction – this is the process of observing the world, gaining knowledge via perception, and then drawing conclusions about unobserved aspects of the world. For instance, one might observe that all the Granny Smith apples one has ever tasted have been tart and conclude that all Granny Smith apples are, have been, and will be tart.
Relations of Ideas – these are claims we come to believe without any sensory experience required. For instance, we can come to realize that a circle has a perfect center point without discovering any perfect circles in the world. All we need to do is think clearly about what it means to be a circle!
Matters of Fact – these are claims about the world that we learn by observation and experience. For example, we have to use telescopes or rovers to discover whether the moon has any water on it or not; we can’t just come to know that the moon has water on it by thinking about the moon clearly.
Constant Conjunction – the observation that some things always occur together, either at the same time or one after another. For instance, there is a correlation, a consistent joint occurrence, between lightning and thunder. As another example, there is a constant conjunction of the heart ceasing to function and the body decaying.
A Priori Reasoning – drawing a conclusion based on relations between ideas, which have strict definitions, rather than drawing conclusions based on our personal experiences. For instance, we can conclude that each circle has only one radius length, which is the distance from any edge of the circle to its center point. We can reason to this conclusion without any personal experience, given that we understand the meaning of the word “radius”, the meaning of the word “center point”, and the meaning of the word “circle”.
Hume wants to prove that human reason is fundamentally flawed. What makes our reason so weak? Well, it is that we rely on experience to support many of our beliefs, yet the experiences we have had in the past don’t give us evidence about what we will experience in the future, or so Hume argues. To show this, he first has to distinguish between two types of claims: (1) relations of ideas versus (2) matters of fact.
Enquiry IV.1.20-21
All the objects of human reason or enquiry may naturally be divided into two kinds, to wit, Relations of Ideas, and Matters of Fact. Of the first kind are the sciences of Geometry, Algebra, and Arithmetic; and in short, every affirmation which is either intuitively or demonstratively certain. That the square of the hypotenuse is equal to the square of the two sides is a proposition which expresses a relation between these figures. That three times five is equal to the half of thirty, expresses a relation between these numbers. Propositions of this kind are discoverable by the mere operation of thought, without dependence on what is anywhere existent in the universe. Though there never were a circle or triangle in nature, the truths demonstrated by Euclid would for ever retain their certainty and evidence […]
Matters of fact, which are the second objects of human reason, are not ascertained in the same manner; nor is our evidence of their truth, however great, of a like nature with the foregoing. The contrary of every matter of fact is still possible; because it can never imply a contradiction, and is conceived by the mind with the same facility and distinctness, as if ever so conformable to reality. That the sun will not rise to-morrow is no less intelligible a proposition, and implies no more contradiction than the affirmation, that it will rise. We should in vain, therefore, attempt to demonstrate its falsehood. Were it demonstratively false, it would imply a contradiction, and could never be distinctly conceived by the mind.
Hume is arguing that when we draw conclusions about the relationship between different concepts, our conclusions can be known with certainty. Because they are true by definition, none of our later discoveries would make us question our original reasoning.
But our everyday experiences of the world aren’t like this at all – we believe all sorts of things because of direct observation or even testimony of the observation of others. And Hume thinks that we cannot be certain of those observations! No matter how many times we experience the sun rising, or food satisfying our hunger, or water satisfying our thirst, we could still conceive of a day when that doesn’t happen. So we shouldn’t claim to be certain that the sun will rise again tomorrow, or that dinner will make us feel full tonight, or that water will make us feel quenched in ten minutes!
To see a philosopher explain the difference between relations of ideas and matters of fact, check out this video by philosopher Daniel Greco.
Why do you still believe there is a bedside table when you close your eyes to go to bed? You no longer see it, feel it, or hear it! You may have had evidence in the past, when you were directly looking at it, but what about now? Hume thinks that when we make claims about stuff we don’t experience directly, it’s because we think that stuff is caused by things we do experience directly. Let’s see some examples of this.
Enquiry IV.1.22
All reasonings concerning matter of fact seem to be founded on the relation of Cause and Effect. By means of that relation alone we can go beyond the evidence of our memory and senses. If you were to ask a man, why he believes any matter of fact, which is absent; for instance, that his friend is in the country, or in France; he would give you a reason; and this reason would be some other fact; as a letter received from him, or the knowledge of his former resolutions and promises. A man finding a watch or any other machine in a desert island, would conclude that there had once been men in that island. All our reasonings concerning fact are of the same nature. And here it is constantly supposed that there is a connexion between the present fact and that which is inferred from it. Were there nothing to bind them together, the inference would be entirely precarious. The hearing of an articulate voice and rational discourse in the dark assures us of the presence of some person: Why? because these are the effects of the human make and fabric, and closely connected with it […]
Hume’s claim that a watch found on a desert island indicates the presence of humans is precisely the sort of causal reasoning used in teleological arguments for the existence of God. William Paley, a contemporary of Hume’s, famously argued that the presence of a watch suggests the existence of a watchmaker. Likewise, the presence of organization in the works of nature suggests the existence of a designer – God. Whatever Hume’s reasons for concluding that humans must once have been on an island where watches are found, that same reasoning applies, according to Paley, to the historical presence of a designer and creator of the universe. Yet, Hume was famously an agnostic, who questioned God’s existence, or perhaps even an atheist who denied God’s existence altogether.
Anytime we form a belief about something we do not directly perceive, we do so ultimately because of some other belief we have, which we got from perceptual experience. For example, we believe that a man is in the room when we hear a human-sounding voice speaking our language, even though we do not see him or feel him. Hume says that we are confident in this conclusion because we have never heard anything that wasn’t human speak our language with a human-sounding voice. Now that we have Alexa and Siri, perhaps we are less quick to draw the same conclusion when we hear a woman’s voice in a dark room!
Enquiry IV.1.23
I shall venture to affirm, as a general proposition, which admits of no exception, that the knowledge of this relation is not, in any instance, attained by reasonings a priori; but arises entirely from experience, when we find that any particular objects are constantly conjoined with each other. Let an object be presented to a man of ever so strong natural reason and abilities; if that object be entirely new to him, he will not be able, by the most accurate examination of its sensible qualities, to discover any of its causes or effects. Adam, though his rational faculties be supposed, at the very first, entirely perfect, could not have inferred from the fluidity and transparency of water that it would suffocate him, or from the light and warmth of fire that it would consume him.
Hume believes that we can only know the ability of water to drown us and the ability of fire to burn us by witnessing it happen (or by being told by someone else that it has happened). This is because we cannot know about the effects that one sort of thing can have on another without first seeing them occur together consistently. The first time we saw someone get burned when near a fire, we could very well have written it off—perhaps the person was burned by chemical exposure, or maybe the sun burned him. It isn’t until we witness it repeatedly that we become confident that fire is the cause of the burns.
Hume plans to show that we can’t be certain about anything that we haven’t experienced firsthand. Yet, he is well aware that we often feel certain about things we have never seen or heard directly.
Enquiry IV.2.29
As to past Experience, it can be allowed to give direct and certain information of those precise objects only, and that precise period of time, which fell under its cognizance: but why this experience should be extended to future times, and to other objects, which for aught we know, may be only in appearance similar; this is the main question on which I would insist. The bread, which I formerly eat, nourished me; that is, a body of such sensible qualities was, at that time, endued with such secret powers: but does it follow, that other bread must also nourish me at another time, and that like sensible qualities must always be attended with like secret powers? The consequence seems nowise necessary.
Ultimately, Hume thinks that we are like a blind man who isn’t aware he is blind, confidently drawing conclusions about things we haven’t directly experienced. We are often so confident in our beliefs; yet when we are asked to explain why we hold them, we are left talking in circles or speaking about imaginary causes or “secret powers.” Hume is not satisfied with these rhetorical devices; he wants certainty about the world around us. Hume is looking for proof that there is some necessary connection between lightning and thunder, in the way that the definitions of “circle” and “radius” and “centerpoint” can prove our conclusion that a circle has only one radius.
The short answer is that, unfortunately, Hume doesn’t think we can find certainty with respect to causes and their effects. All sorts of things could happen that we don’t believe ever would happen. And unfortunately, we just don’t have good reasons for rejecting those outlandish possibilities.
Enquiry IV.2.30
[…] [I]t implies no contradiction that the course of nature may change, and that an object, seemingly like those which we have experienced, may be attended with different or contrary effects. May I not clearly and distinctly conceive that a body, falling from the clouds, and which, in all other respects, resembles snow, has yet the taste of salt or feeling of fire? Is there any more intelligible proposition than to affirm, that all the trees will flourish in December and January, and decay in May and June? Now whatever is intelligible, and can be distinctly conceived, implies no contradiction, and can never be proved false by any demonstrative argument or abstract reasoning priori.
In the film Cloudy with a Chance of Meatballs, cheeseburgers rain down from the sky, and spaghetti and meatballs form a tornado. Similarly, according to Hume it is entirely possible that tomorrow it will begin raining salty, burning, white chunks. After all, we aren’t psychics, and we don’t have weather models that forecast food weather events!
According to Hume, our past experience is no indication of our future experience, and so we cannot use our past experience to form beliefs about the present or the future. But things are even worse than that. Hume claims that all our beliefs about cause and effect depend on a kind of circular reasoning. Circular reasoning occurs when I draw a conclusion from other beliefs I have that are actually supported by the conclusion itself.
Enquiry IV.2.30
If we be, therefore, engaged by arguments to put trust in past experience, and make it the standard of our future judgement, these arguments must be probable only, or such as regard matter of fact and real existence, according to the division above mentioned. But that there is no argument of this kind, must appear, if our explication of that species of reasoning be admitted as solid and satisfactory. We have said that all arguments concerning existence are founded on the relation of cause and effect; that our knowledge of that relation is derived entirely from experience; and that all our experimental conclusions proceed upon the supposition that the future will be conformable to the past. To endeavour, therefore, the proof of this last supposition by probable arguments, or arguments regarding existence, must be evidently going in a circle, and taking that for granted, which is the very point in question.
In the passage above, Hume is reconstructing his opponent’s argument to show that it is circular and therefore illogical. Here is how an argument about the similarities between various fires would look, according to Hume:
Principle of Uniformity of Nature (PUN). Things of a certain kind that we experience in the future will be similar to those of that same kind that we experienced in the past.
Conclusion: Therefore, the fires experienced in the future will be similar to the fires of past experience.
Since PUN might possibly be false, we need to defend it with an argument. Hume thinks that the only sort of argument we could give for PUN would look something like this:
Premise 1: Things in the recent past have resembled the same sorts of things that occurred in the more distant past.
Premise 2: If the more distant past resembles the more recent past in the way described in (1), then the future will resemble the more recent past in the same way.
Conclusion: PUN. Therefore, things of a certain kind that we experience in the future will be similar to those of that same kind that we experienced in the past.
But why think premise (2) is true? Hume thinks that we can only accept (2) because we believe “that instances, of which we have had no experience, must resemble those, of which we have had experience, and that the course of nature continues always uniformly the same.” (Treatise 1.3.6.4) But this just is the Principle of the Uniformity of Nature; it is a restatement of PUN, which is what (2) is meant to support! Thus, premise (2) supports PUN, but (2) is itself supported by PUN, making the argument circular.
Hume ultimately admits that we cannot refuse to form beliefs about causes and their effects. We naturally form beliefs about things we don’t directly observe, including stuff we think will happen in the future. We are human, and humans rely on past experience and future expectations to survive. This sort of reasoning, which Hume calls induction, is a tool we use in everyday life, but it may not be rational or reasonable after all.
Enquiry IV.2.31
In reality, all arguments from experience are founded on the similarity which we discover among natural objects, and by which we are induced to expect effects similar to those which we have found to follow from such objects. And though none but a fool or madman will ever pretend to dispute the authority of experience, or to reject that great guide of human life, it may surely be allowed a philosopher to have so much curiosity at least as to examine the principle of human nature, which gives this mighty authority to experience, and makes us draw advantage from that similarity which nature has placed among different objects. From causes which appear similar we expect similar effects. This is the sum of all our experimental conclusions. Now it seems evident that, if this conclusion were formed by reason, it would be as perfect at first, and upon one instance, as after ever so long a course of experience. But the case is far otherwise. Nothing so like as eggs; yet no one, on account of this appearing similarity, expects the same taste and relish in all of them. It is only after a long course of uniform experiments in any kind, that we attain a firm reliance and security with regard to a particular event.
Surprisingly, Hume thinks that we can and should continue to stick to our experience as a guide to living. We can’t live life without doing so, and we would be crazy to try. Yet, when we actually look at our past experiences, we realize that uniformity and order are the primary reasons for the beliefs we hold about the future or about things we haven’t directly witnessed. And, as it turns out, we probably don’t have much proof that the world is uniform and orderly in the ways we assume.
Hume’s final nail in the coffin for experiential reasoning comes in the following passage, when he argues against assigning some special powers to the things around us, powers that explain why many of the same sorts of things appear and behave similarly .
Enquiry IV.2.32
[Experience] only shows us a number of uniform effects, resulting from certain objects, and teaches us that those particular objects, at that particular time, were endowed with such powers and forces. When a new object, endowed with similar sensible qualities, is produced, we expect similar powers and forces, and look for a like effect. From a body of like colour and consistence with bread we expect like nourishment and support. But this surely is a step or progress of the mind, which wants to be explained. When a man says, I have found, in all past instances, such sensible qualities conjoined with such secret powers: And when he says, Similar sensible qualities will always be conjoined with similar secret powers, he is not guilty of a tautology, nor are these propositions in any respect the same. […] Their secret nature, and consequently all their effects and influence, may change, without any change in their sensible qualities. This happens sometimes, and with regard to some objects: Why may it not happen always, and with regard to all objects?
As we have seen, Hume claims that inductive reasoning is circular reasoning, because we can only support our conclusion by defending the Principle of the Uniformity of Nature. We must, in the end, admit that we believe without evidence that the course of nature is uniform and orderly, that the future will resemble the past.
To listen to a philosopher explain the circular reasoning underlying induction, check out this second video by philosopher Daniel Greco.
Hume takes himself to have shown that inductive or probabilistic reasoning, though common to all humans in everyday life, is not the sort of reasoning we can rely on to gain genuine knowledge about the world. Yet, he admits that life goes on with this sort of reasoning every day — we often reason inductively, even though the constant conjunctions we see in the world could fail us at any time.
Hume’s theory of knowledge and reasoning has direct applications to his theory of morality. He argues that practical reasoning is not guided by objective principles that we discover through demonstrative reasoning. Rather, our actions towards others are guided by sympathy, which we develop by making inductive, probabilistic connections between our own emotions and desires and the emotions and desires of others. But just as we have no good reason to think that nature is orderly rather than chaotic, we also have no good reason to think that moral action is guided by universal ethical principles. We use the past experiences we’ve had to develop moral emotions toward others, and those emotions and desires inform how we treat others in the future. But unfortunately, there isn’t anything outside of us that explains why we should care about others at all!
For a short summary of the Problem of Induction, check out this essay from 1000-Word Philosophy, and for an in-depth overview, especially as it relates to contemporary philosophy, check out this Stanford Encyclopedia of Philosophy article. For a discussion of Hume’s broader philosophy, check out this Stanford Encyclopedia of Philosophy article.
This work has been adapted from An Enquiry Concerning Human Understanding, a title from The Project Gutenberg’s ebook collection. Thanks to Wes Siscoe and an anonymous reviewer for their comments on an earlier draft of this article. This work is in the public domain. All images were created using Midjourney.
Moses, Katherine. 2026. “The Sun’ll Come Up Tomorrow! (Right?) David Hume’s An Enquiry Concerning Human Understanding, Section IV.” The Philosophy Teaching Library. Edited by Robert Weston Siscoe, <https://philolibrary.crc.nd.edu/article/the-problem-of-induction/>.
Relations of Ideas – these are claims we come to believe without any sensory experience required. For instance, we can come to realize that a circle has a perfect center point without discovering any perfect circles in the world. All we need to do is think clearly about what it means to be a circle!
Here, Kant refers to Frederick the Great (Friedrich II, 1712-1786), who was King of Prussia. A supporter of the Enlightenment, Frederick endorsed social and political change by abolishing torture and expanding the educational sector. He suspended censorship for newspapers with the exception of political content. Supporting freedom of religion in general, he nevertheless favored protestants for political higher office and did not grant Jews civil rights.
Monarchy – A monarchy is a state where political deliberation is performed by one person (generally a king or queen).
Phalaris (c. 570-549 BCE) was, by most accounts, the very opposite of Cyrus, and he was used as an example of tyrannical cruelty in antiquity. He was tyrant of Acragas (now Agrigento) in Sicily. Diodorus Siculus records an infamous account of Phalaris’s torturing his enemies in a bronze bull placed over a roaring fire.
Cyrus the Great (d. 530 BCE) was the first emperor of the Persian Empire and a commonly used exemplar of the “enlightened monarch” in antiquity. He was renowned for his tolerance and care for his subjects. Xenophon, a student of Socrates, wrote a partly fictionalized biography of Cyrus called The Education of Cyrus (Cyropaedia). Peter Drucker, an influential 20th-century management theorist, called the Cyropaedia the best book on leadership.
Republic (res publica) – Cicero’s short definition of res publica is res populi (the ‘people’s thing’). Later in the Republic, Cicero famously defines a republic (1.39) as an assemblage of people associated with each other by consensus on justice (ius) and mutual benefit (utilitas).
Scipio Aemilianus Africanus was a hero among many Romans, but his reputation today is far less straightforward. Scipio Aemilianus led a Roman military campaign resulting in the utter destruction of the city of Carthage in 146 BCE. The Carthaginians were a prosperous Phoenician people in North Africa and rivals to Roman power. It has been argued that this act of ‘national extermination’ meets the modern definition of genocide. How should this knowledge impact how we view Scipio’s political philosophy expressed here?
This famous phrase, known by the abbreviation SPQR (senatus populusque Romanus), served as something like the official title of the Roman state (compare ‘USA’, ‘USSR’, ‘UK’), and encapsulated the ideal of a res publica (common property in public hands shared between the people and a council of elders).
Contemplation: The activity of human beings’ rationality. Contemplation is more than just thinking; it’s thinking excellently about ultimate truths. Contemplation is the ultimate activity associated with human flourishing.
Eudaimonia: Often translated as ‘happiness’ (in this text) or ‘flourishing’, eudaimonia is the activity of living the best possible life for a human being. Eudaimonia is more than just feeling happy or contented – it’s the idea that there is a best way to live for human beings.
Virtue: Virtues are cultivated tendencies to perform our function excellently, which allow us to reliably do the right thing, to the right extent, for the right reasons, given the demands of a specific circumstance. There are three components of virtues: virtues involve (a) skillful activity – they’re excellences after all!, (b) proper motivation, and (c) appropriate judgment – they often lead to judgments about what is the right thing to do, which requires careful attention to the circumstances.
Pleasure: The enjoyable feeling that accompanies some activities. Some philosophers (but not Aristotle!) think that pleasure is the only thing that is good in itself
Endoxic Method: An argumentative structure that begins by laying out the endoxa, or the beliefs of the many or the wise, then raises apparent problems for those views and develops a resolution to those problems.
The Problem of Induction: A problem for reasoning about the future based on past experiences. How can we be justified in believing that patterns of events in the past will continue into the future?
A Priori: Hume is using the term ‘a priori’ to denote the kind of reasoning that allows one to gain knowledge as relations of ideas—in other words, reasoning from one necessary, definitional truth to another.
Justification: the concept of justifying one’s thinking, or one’s beliefs, is important in epistemology. Roughly, one’s thinking or belief is justified when there is good reason for it, or when it is well supported or well evidenced. All of these are ways of referring to some connection between what we think or believe and what is, or to some way of at least making ourselves think that we are closer to the truth.
Inference: The psychological process of moving from one thought to another, such as moving from the thought “it’s raining, and I don’t want to get wet” to “I should get my umbrella”, or from “I am tired, and it’s getting late” to “I should get some sleep”. Nowadays, philosophers tend to use the term ‘inference’ to mean the same as ‘reasoning’, and tend instead to use the term ‘association’ to refer to movements between thoughts that are not based on any logic or evidence.
Matters of Fact: Knowledge that is gained by experience, such as by observing or experimenting with objects in the world. For example, knowing whether all swans in the world are white requires somebody to examine the many swans in the world and make sure they do not happen to discover a black one (and in fact, there are black swans!).
Relations of Ideas: Knowledge that is gained just by sufficiently clear thinking, without having to observe or experiment with objects in the world. For example, knowing that a triangle has three sides is something you can know just because of what it means to be a triangle, hence without having to carefully examine triangular objects that you find throughout the world.
Reasoning: Developing arguments to try and support the truth of one’s beliefs.
Causation: A relation between events, where one event (cause) is responsible for another (effect). Eating too much chocolate can cause the effect of having an upset stomach, and not getting enough sleep can cause someone to be grumpy.
Epistemological Theories: Theories about the nature and possibility of knowledge – whether, when, how, and to what extent we can know about reality, such as the physical world, or our own consciousness. For example, one epistemological theory says that we can gain understanding of our own consciousness by studying the brain, whereas other theories say that we can only gain knowledge of consciousness by reflecting on our own inner experiences.
Aristotle means “happy” in the sense of a person who has developed a complete character, lived a full life, and become a true example of human goodness.
Happy Person – Someone who has developed her entire self well and lived a complete and flourishing life. She is a real and positive example of how we should live.
This is where Aristotle defines virtuous friends. These are friends who you actually answer the phone for. These are the friends who you ask for advice on work, love, and life. They are the friends that celebrate you for being you, but they also tell you when you’re messing things up. Not only do they love you, but you love them and try to be the same kind of friend to them too.
This is where Aristotle defines pleasurable friends. These are your TikTok, Snap Chat, or Instagram friends, the ones you post to social media when you’re having a good time.
This is Aristotle’s explicit definition of useful friends. These are your LinkedIn friends, those who you like networking with at events or enjoy working with on projects.
Virtuous Friendship – A friendship where people set as their goal for their friendship becoming good people together and living happy lives just because they value the good of their friends as persons. These are also known as “perfect” or “true” friendships. They are usually between people who are equally good. And they might be limited to people of equal social status, wealth, and power. Aristotle doesn’t think that any happy person will lack virtuous friends. But he thinks it’s likely that we’ll only have a few of this sort.
Pleasurable Friendship – A friendship where people set as their goal for their friendship some pleasant goal, such as friendship between people who go out on the town together. These friendships are plentiful and easy to form and dissolve.
Useful Friendship – A friendship where two people set as their goal for their friendship some useful or utilitarian purpose, such as friendship between work colleagues. These friendships are plentiful and easy to form and dissolve.
Aristotle uses “friend” broadly for any relationship between people who like each other, wish good things for each other, and get something out of spending time together.
Friendship – A relationship between two people who like each other, generally wish each other well, and have a goal for their interactions.
Happiness – The final end and highest good of human life. The perfect good that objectively fulfills human nature and subjectively satisfies desire.
Happiness Criteria – The conditions that the true object of happiness must satisfy. They are: finality, intrinsic value, purity, internality, authenticity, stability, self-sufficiency, completeness.
Object of Happiness – The thing in which happiness essentially consists, the attainment of which will make us truly happy.
Highest Good – The greatest good for a human being.
Final End – The ultimate goal of human life. All of our other goals are chosen for the sake of this final end.
Constituent Principles – Parts of a material object that cause the object to be the sort of thing that it is, but that cannot be removed from that object (in the way that some properties can be gained or lost). For Aquinas, this would include things such as form (the structure of a material object) and matter (that which is structured). For example, Dylan’s form is his soul, and his matter is his body. His soul and body are distinct, but Dylan could not exist if he were not composed of both.
Accident/accidental property – A property that something can possess or not possess while still remaining the thing that it is. For example, Dylan could grow taller, or he could stop being musical, without becoming a different person. By contrast, rationality is an essential property of Dylan, since being rational is part of the “what it is to be” of a human being.
Subject/Suppositum – Something or someone that can bear properties but is not itself a property that something else can bear. Dylan can have properties, like being short or being musical, but no one can have Dylan as a property.
Property – A feature that an object has. For example, a ball could be orange, which means that the ball has the property of orangeness. In many cases a property can be gained or lost. The ball could be painted green, in which case it would gain the property of greenness and lose the property of orangeness.
Actuality – The being, or act of being, of a thing. For example, hot water is actually hot (the water is hot), even though it is potentially cold. Likewise, a boy is actually a human being (he is a human being), even though he is also potentially a full-grown man (and he will still be an actual human being when he becomes a full-grown man).
Potentiality – Ways a given thing can become different from the way it is now. For example, cold water is potentially hot, since it can be heated up, and an acorn is potentially an Oak tree since it can grow to full size under the right conditions.
Essence – The “what it is to be” of a thing. For example, the essence of a human being is to be a rational animal, and the essence of a cheetah is to be the fastest land animal.
Principle of Specialization – The idea that work is more efficient and more effective if each worker specializes in exactly one task.
Extrinsic Value – Value a thing has that is dependent on something else. Extrinsically valuable things are worth pursuing because they get you something else that is valuable. Money, for instance, is only useful because it can be exchanged for other things.
Intrinsic Value – Value a thing has independently or inherently. Intrinsically valuable things are worth pursuing for their own sake.
Adeimantus and Glaucon were Plato’s older brothers (along with an older sister, Potone). They were both honored for military valor at a battle with Megara. We know little about their lives otherwise. Potone had a son, Speusippus, who inherited leadership of the Academy upon Plato’s death.
Thrasymachus was a real person, who lived about 459-400 BCE moved to Athens from Chalcedon to become a sophist (a professional teacher and public speaker). Only a few fragments of his work survives
Prudence – Prudence is virtue wherein a person is able to choose, in any given situation, the course of action that will lead to greater happiness. For example, a prudential person knows when it is appropriate to continue a difficult conversation and when it is best to wait for a more appropriate time.
Pleasure – Epicurus would have us think about pleasure as coming in two forms: moving and static. Moving pleasures are the type that we experience in the process of satisfying a desire (this coffee tastes amazing!). Static pleasure is the feeling of being satisfied — no longer experiencing need or want (I am feeling so peaceful sitting in the park). Epicurus thinks these static pleasures are the best sort.
Epicurus believed that reality is composed of matter. This sets him apart from other philosophers of the time who, often influenced by Plato, believed that reality is composed of both the material and immaterial (like the soul, or the Platonic forms).
Happiness – Epicurus uses the Greek word “eudaimonia,” which is typically translated into English as “happiness.” Whereas today happiness is most often used to describe a momentary feeling (this new notebook makes me happy!) Epicurus means something more like a consistent state of well-being and contentment.
Unconditioned: an ultimate explanation of reality. For example, if I explain why it is raining today by appealing to some atmospheric conditions, I can always ask for the cause of those conditions, and so on. Only a cause that is not caused by anything else (something unconditioned) would give us an ultimate explanation.
Transcendental Idealism: Kant’s mature philosophical position. It holds that appearances are not things in themselves, but representations of our mind. It is opposed to transcendental realism, which identifies appearances with things in themselves.
Appearances (vs. things in themselves): things as they are experienced by us (also known as phenomena). They should be distinguished from things as they are independently of our experience (things in themselves or noumena).
Metaphysics: the study of what there is. Traditionally, metaphysics is divided into general metaphysics and special metaphysics. The former investigates the general features of reality and asks questions such as ‘What is possible?’. The latter studies particular kinds of being and asks questions such as ‘Does God exist?’ or ‘Is the soul immortal?’.
Reason: the faculty that knows a priori. Kant uses this term in a general sense (the knowing faculty as such) and in a specific sense (the faculty that demands ultimate explanations).
A priori: term denoting propositions that can be known independently from experience. For example, propositions such as ‘All bachelors are unmarried’ or ‘The whole is greater than its parts’ can be known without recourse to any experience.
Make sure not to think that ‘unjustified’ means ‘false.’ Even if they are true, the point is just that this would not be something that had been shown.
‘Absolute’ might be a confusing word, here. Socrates means that the geometers are not reasoning about their drawing of the square, for example, but of the square itself. They do not conclude that, for the square they drew, the area is equal to the square of a side – they conclude that this is true for squares as an intelligible object, or, as Plato would say, the Form of the square.
By ‘science’, Plato means to be talking about all rational disciplines, including mathematics.
The form of the beautiful has to be perfectly beautiful because all instances of beautiful things are explained by it, so it has to be responsible for the highest possible degrees of beauty possessed by anything. Moreover, it has no trace of ugliness in it.
The form of the beautiful has to be immaterial because all the many beautiful things do not share any material – that is, they are all made of different stuff.
Form (εἶδος / ἰδέα) – Intelligible, immaterial, perfect entities that explain the unity among the many things which share the feature named by the entity (e.g., Beauty, Squareness, Oddness). For example, think of a square. There might be many different squares, but they all share features like having four sides of equal length. So, the Form of Squareness would include all of those features that make something a square.
Guardian – This is the name Plato gives to the ruling class in his ideal city. Think of them as philosopher kings – they have complete control over the organization of the state. The Republic is partially about why Plato thinks they would be needed for an ideal system of government and what they would need to learn to do the job well.
Plato has previously argued that we are made up of different parts. The first part is the appetitive which is responsible for our desires for food, sex, and other bodily needs. Then there is the spirited part, which longs for fame and honor. Finally, he identifies the rational part, which discerns what is good and bad for us through reason. The parts can all come into conflict with one another, and managing their relations is what Plato thinks justice is all about.
Soul (ψῡχή) – What Greeks meant by this word is controversial. For now, think of it as the thing that makes you different from a rock or other objects, the thinking and experiencing part of you as well as the part of you that acts and makes decision. You might use the word ‘mind’ or ‘self’ to talk about this.
Virtue – Virtues are the character traits that make a person good. For example, most people consider courage and generosity to be virtues. English-speakers usually reserve the word ‘virtue’ for human beings, but in ancient Greek the word can be more comfortably applied to other beings as well.
Was it his burly physique, his wide breadth of wisdom, or his remarkable forehead which earned him this nickname?
Aporia – A Greek term for “being at a loss” or “clueless.” Socrates often questions people until they have no idea how to define something that they thought they understood.
You might be confused by the word ‘attention’ below. In Greek the word is therapeia, from which we get the English word ‘therapy.’ It primarily means the same as ‘service’ as in ‘to serve,’ but shades into ‘worship,’ ‘take care of,’ and ‘attend to.’
Meletus – A poet and citizen of Athens and one of Socrates’ accusers. Amongst other things, Meletus accused Socrates of impiety and corrupting the youth.
Divine Voluntarism – The idea that God is free to determine even the most basic truths. If divine voluntarism is true, then God could have made it so that 2+2=5 or so that cruelty and blasphemy are holy and good.
Euthyphro Dilemma – The question, “Is a thing holy because the gods love it, or do the gods love it because it is holy?” The general idea of a forced choice (or “dilemma”) about the true order of explanation occurs often in philosophy and gets referred to by this term.
Essence – What a thing fundamentally is. A square might be red or blue without changing the fact that it’s a square, but a square must have four sides, so having four sides is part of a square’s essence.
Definition – The perfect description of a thing. A definition should pick out all and only examples of a thing. For example, ‘bachelor’ might be defined as ‘unmarried man,’ because all unmarried men are bachelors, and only unmarried men are bachelors.
In Disney’s retelling of the Hunchback of Notre Dame, the clergyman Claude Frollo orders the death of many Roma on religious grounds. It is clear, however, that he is really motivated by spite and his unrequited lust for the Romani woman Esmerelda.
Spanish conquistadors were shocked by the scope of ritual human sacrifice among the Aztecs, as hundreds or even thousands of people were sacrificed each year. The Aztecs thought that the sacrifices could repay the sacrifices the gods had made in creating the sun and earth.
Zeus – The god of sky and thunder in ancient Greek mythology, Zeus was depicted as chief among the gods and called the father of the gods and men.
Forms – The perfect, divine, and intelligible entities that exist independently of the physical world. They are comprehensible only through reason, not through our senses, and their existence explains the properties of objects in the physical world.
Recollection – The soul existed prior to birth; during this time it learned everything, and hence all learning is only recalling what we already know.
Immortality of the Soul – Unlike the body, the soul is not subject to physical death, because it is immortal and indestructible.
Philosophy – The practice of preparing the soul for death by training it to think and exist independently of the body
Death – Plato understands this as the soul’s separation from the body
Human Identity Across Time – Locke’s notion that any human stays the same across time if, and only if, it maintains the same (distinctively human) organizing structure of parts.
Substance Identity Across Time – Something is the same substance across a segment of time if, and only if, it continuously exists across the relevant segment of time without gaining or losing any of its parts.
Immaterial Soul – A personal thinking substance without any physical constitution.
Personal Identity Across Time – Whatever makes someone the numerically same person (i.e., that very person) at different times; according to Locke, it is a relation of first-person consciousness via memory.
Person – Locke’s forensic definition of person (pertaining to courts of law regarding the justice of praise, blame, reward, or punishment): a thinking, intelligent being, that has reason and reflection, and can consider itself as itself, the same thinking thing in different times and places.
The Prophet Muhammad is a central figure in Islam. He is viewed as the last of a long line of prophets, which includes Moses and Jesus. He is responsible for writing the Quran, which was dedicated to him by the angel Gabriel. His life and sayings are recounted in the Hadith; he is viewed as an exemplary role model of Islamic life and faith.
Exhortation — The method of understanding and interpreting Truth available to the common people. The majority of people take scripture literally and understand truth and right action based upon this understanding. They are persuaded by the vivid imagery of the Quran and the rhetorical exhortations of religious leaders. Averroes takes this to be lowest form of understanding
Dogmatic Discourse — The method of understanding displayed by those who, through natural ability and habit, are able to have a deeper understanding of the Quran, and of the truths it illuminates. These people know that not all of the scriptures are to be taken literally, and that greater underlying Truths are revealed by interpreting some elements allegorically. Still, they err on the side of dogmatism and literal interpretation whenever uncertainty arises. Averroes associates this way of thinking with Muslim theologians and views this to be the middle level of understanding.
Philosophical Inference – The type of understanding associated with philosophical demonstration or argument. This is the highest level of understanding, accomplished by a select few, who have a natural capacity for philosophy and proper philosophical training.
Law — The Quran (the central religious text of Islam) and, to a lesser extent, the Hadith (reports of what the prophet Muhammad said and did). Averroes is concerned with explaining how philosophy relates to what Muslims take to be the unerring Truth regarding God and the nature of existence, as they are expressed in Scripture.
Occasionalism — a theory claiming that God is the only true cause of changes in the world. For example, when you high-five me, you’re not really the cause of the stinging sensation I experience. God is the cause. Your high five is just the occasion on which God causes it.
Interactionism — a theory claiming that things in the world can truly cause changes in each other. For example, when you high-five me, you truly cause me to experience a stinging sensation in my hand.
Substance Dualism — a theory claiming that the mind (or soul) and body are two distinct and very different things.
Body — what it sounds like! The body is the physical part or aspect of a thing and has characteristics like shape, size, etc.
Soul — that part or aspect of a thing involving mental aspects of their existence, e.g., thoughts, feelings, decisions, etc. The “soul”, in this sense, is more or less just the mind.
Causal Interaction — When one thing acts (i.e., itself does something) and in so acting makes another thing change. For example, when you high-five me, you cause me to experience a stinging sensation in my hand.
God as God – The phrase “God as God” is basically a synonym for “God the subject.” In other words, it refers to God precisely in God’s status as an incomprehensible divine Other.
Incarnation – The Christian doctrine of the incarnation is the notion that the word of God became fully human in the person of Jesus of Nazareth. It is closely associated with the doctrine of the trinity, which asserts that God the Father, God the Son (Jesus as the word made flesh), and God the Holy Spirit are one God.
Religious Fanaticism – In Feuerbach’s use of the term, a religious fanatic is someone who is unwaveringly faithful to God as an utterly mysterious superhuman being. They subordinate other things—especially the love of other humans—to submission before this divine other.
God the Subject – When Feuerbach refers to God as a subject, he is referring to the commonplace religious belief that God is a being who has various attributes, like a loving nature.
Faith Separates Man From God – Faith separates God from man in this sense: it treats God as a mysterious other, a being radically distinct from us.
Faith – Belief in and fidelity to a transcendent divine subject like God.
Orthodoxy – Orthodoxy refers to “right belief,” and it is concern with identifying heresies and ensuring that people believe and practice correctly.
Indirect Form of Self-Knowledge – Feuerbach’s view is that religious belief is a naive way of relating to our human nature and its perfections. It is naive or childlike because it treats these as external realities that belong to God. He believes a mature and contemplative person realizes these don’t belong to God, but rather to our species, abstractly conceived.
Above the Individual Man – The human perfections are “above the individual” insofar as no particular individual ever perfectly realizes them. They are abstractions.
Divine Trinity – Feuerbach is having fun here. He is using the theological phrasing of the Trinity to talk about human perfections. In calling reason, love, and freedom of the will “divine,” he means they are absolutely good; they are activities whose goodness is intrinsic to their practice or exercise. This isn’t a novel philosophical view. For example, Immanuel Kant argued that autonomy or a good will is the only thing which is unconditionally good.
Perfections – The end to which a faculty or power is ordered. For example, omniscience would be the perfection of the intellect. Traditionally, God is said to possess all perfections.
Love – When Feuerbach writes about love, he is referring to unconditional concern for others and the desire for fellowship with them. He is here asserting that love, understood in this sense, is the perfect activity of the affective faculty. In other words, our feelings and passions are fully actualized and engaged in an intrinsically valuable activity when we genuinely love others.
Infinite – The infinite is whatever can be understood as unbounded or unlimited. Human nature in the abstract is unbounded and unlimited. It is only bounded or limited in its concrete form as it is realized by particular material individuals.
Higher Consciousness – The sort of consciousness that mature human beings possess, but which other animals do not. It is “higher” than animal consciousness because it involves thinking abstractly about the form or essence of things.
Science – Feuerbach uses the term science in its classical sense, meaning systematically organized knowledge. Any body of knowledge founded on an understanding of first principles and the essences of things is a science in this sense.
Popular Sovereignty – The view that a government’s authority to rule comes from the people, making a ruler subject to the will of their citizens.
The Divine Right of Kings – The theory that kings are chosen by God and thus that political revolt is a rebellion against the will of God.
Synthesis – The prefix ‘syn-’ means “together,” so a synthesis “brings together” or combines elements of both a thesis and its antithesis.
Antithesis– An antithesis is the contradiction of a thesis. For example, internationalism could be understood as the antithesis of nationalism.
Thesis – In Hegelian terms, a thesis can be understood as a position or theory. Examples include any of the “-isms” that we discuss in science, history, and philosophy, such as Darwinism, capitalism, nationalism, etc.
Progressor’s Temptation – a unique temptation for those making progress in which pride impedes their further progress and leads to backsliding.
Progressors – those who are not yet expert Stoic practitioners, but who are also aware of the fact that they must change their lives in that direction. They are working on making progress.
Intellectualism – the philosophical view that our motivations and emotions are all judgments. The reason why you do something, your motivation, is because you believe it’s the right thing to do. The reason why you feel good or bad about something, an emotion, is because you believe that something good or bad happened to you.
Duties – acts of service, obedience, and respect that we owe to each other. The duties we owe to each other depend on what kind of relationship we have.
Askeses – exercises of Stoic thought and practice that make the lessons and habits of Stoic philosophy second-nature for Stoic practitioners.
Externals – things that are not under our control but that are all-too-easily confused with things that should be important to us, like wealth, status, and pleasure. Too many people believe externals like these are necessary for the good life, and the Stoic path is to focus not on these things but rather what is up to us.
The Fundamental Division – the division between things that are under our direct control and those that are not. The important lesson is to care only about the things we can control.
The Greatest Happiness Principle – A principle which says that actions are right insofar as they promote happiness and wrong insofar as they promote unhappiness
Higher and Lower Pleasures – Types of pleasures that differ in terms of their quality. Things like food and drugs create lower pleasures. Things like intellectual pursuits and doing the right thing create higher forms of pleasure.
The Doctrine of Swine – An objection that utilitarianism entails that if people would be happy rolling in mud, that’s what would be morally best for them to do, so we should reject the theory.
Utilitarianism – A normative theory of which actions are right or wrong. Utilitarianism says the right action is that which maximises utility.
Jeremy Bentham – Considered by some as the father of utilitarianism, Bentham was a moral philosopher and one of John Stuart Mill’s teachers
Epicurus – an ancient Greek philosopher and one of the first to advocate that the ultimate good is experiencing pleasure and avoiding pain.
Utility – The thing that is ultimately valuable in itself. For Mill, this is happiness, which he then understands as pleasure and the absence of pain.
Contract Theory – a modern political theory identifying consent as the sole justification for government. Contract theory is associated with Thomas Hobbes (1588-1679), John Locke (1632-1704), Jean Jacques Rousseau (1712-1778), and more recently, John Rawls (1921-2002)
Prejudice – a foundational, strongly held, unreasoned (but not necessarily irrational) moral opinion or belief. We might believe, for example, that parents have special obligations towards their own children.
A Priori – a philosophical term of art meaning (in Latin) “prior to experience,” which refers to knowledge that is innate or arrived at purely through reasoning, like the truths of mathematics.
Rights – moral claims invoking immunity from (or entitlement to) some specific treatment (or good) from others. Commonly recognized rights include the right to free speech or the right to healthcare.
Reform – a change in the social order that originates from the existing character of society. An example would be market-based healthcare reform in a capitalist society.
Conservatism – a modern political ideology that aims to preserve and promote the existing (or traditional) institutions of society. These institutions typically include the rule of law, property, the family, and religion.
Contingent Being – A being that can fail to exist. Its existence is not guaranteed. This being might come to exist or it might not.
Necessary Being – A being that can’t fail to exist. Its non-existence is impossible. This also means that such a being has always existed.
Want to read more about why the infinite regress option doesn’t work in the Second Way? Check out Sean Floyd’s entry in the Internet Encyclopedia of Philosophy.
Efficient Cause – An efficient cause is something that directly makes another thing exist or move. An example of this is when I kick a ball down a hill. I am the efficient cause of the ball rolling down the hill because I make it move down the hill.
Infinite Regress: Begin with some fact. We begin to explain that fact by appealing to another fact, where these facts are related by either causality or dependence. To create the regress, you keep appealing to more and more facts about causality and dependence without end.
Actuality – An ability or action something is currently exercising. Imagine that I am sitting comfortably at my desk, and then I stand up to take a break from reading. In this case, I am now actually standing.
Potentiality – What something has the capacity to do, but isn’t currently doing. Imagine I am sitting comfortably at my desk. Even though I’m not currently standing, I have the capacity to be standing. So, even while I’m not standing, I have the potential to stand.
Theists and Non-Theists – A theist is someone who believes that God exists, while a non-theist does not. Non-theists include atheists, who believe that God does not exist, and agnostics, who are uncertain about whether God exists.
Glaucon – one of Plato’s brothers and one of Socrates’ main interlocutors in the Republic dialogue. In that dialogue, he challenges Socrates to provide a compelling justification for why one should be a just person beyond merely following conventions or avoiding punishment. This sets up Socrates’ defense of justice as intrinsically worthwhile. Throughout the Republic, Glaucon prods Socrates to fully explain his theories of the ideal society, philosopher-kings, and the Form of the Good.
Aristotle – a Greek philosopher (384-322 BC) who studied under Plato and went on to be one of the most influential philosophers to ever live. Simply called “The Philosopher” by Thomas Aquinas and others in the medieval period, Aristotle’s views would eventually be synthesized with Christian theology, laying the intellectual foundation for later scholarly developments in Western Europe.
Understanding – Socrates describes education as turning one’s “understanding” in the right direction. The word “understanding” here translates the ancient Greek term “to phronēsai,” which means “understanding,” “being conscious,” or “having insight.” People who are wicked focus their “understanding” on how best to accomplish their selfish and narrow desires. Those who are wise, in contrast, have learned to focus their “understanding” on what is truly good and beneficial.
The Form of the Good – Socrates characterizes the ultimate goal of education as coming to know “the Form of the Good.” The Form of the Good is his technical term for the meaning of goodness: what it is to be good. Socrates is clear that this “knowledge of the Good” is not simply theoretical knowledge, but also knowledge in the sense of “knowing how”: knowing how to achieve what’s good, to do what’s good, to accomplish what’s good. Mere “book knowledge” or simply being smart is not enough.
The Intelligible – Socrates uses “the intelligible” to name the aspects of the world that we can only grasp through thinking or insight. With my eyes I can see the tree outside my window, but what it means to be a tree is something I can only comprehend in thought. Likewise, I can see the people around me, but human nature, human dignity, and what it means to be human is something I can only grasp conceptually. “The intelligible” is the world insofar as it “makes sense” and can be comprehended.
The Visible – By “the visible,” Socrates means those aspects of the world we can perceive with our five senses and our imagination—those aspects of the world we can see, hear, taste, smell, touch, and imagine. For example, with my eyes I can see the sky, trees, people around me, and so on as visible things. “The visible” is the world insofar as it can be perceived and imagined.
Education – Socrates says that the allegorical story he tells represents the effect of education on human nature. “Education” here is a translation of the ancient Greek word “paideia,” which means “education” in the widest sense of the term. “Paideia” doesn’t mean “education” in the sense of going to school or getting good grades. Instead, it refers to the process of becoming a wise, intelligent, good, and well-rounded human being.
Allegory – An allegory is a symbolic narrative where characters, events, and/or settings represent abstract ideas or convey deeper meanings beyond the literal story. Socrates tells such a symbolic narrative in the passages below. The characters, events, and setting of his narrative symbolize the effect of what he calls “education.”
Self-knowledge – Knowledge of the contents of one’s own mind, such as one’s own beliefs and desires. Self-knowledge can be gained through introspection, that is, by reflecting on what one thinks and experiences. Some philosophers believe that self-knowledge has special properties that our knowledge of the external world lacks, such as being clearer, more reliable, or more valuable.
Dualism – The view that the mind is entirely distinct from the body. This view is usually contrasted with different kinds of monism, which hold that the mind is ultimately just a part of the body (materialism) or that the body is ultimately just a part of the mind (idealism). Dualists hold that the mind and the body are fundamentally different aspects of reality, and both categories are needed to properly describe the universe, especially the human person.
The Self – What the ‘I’ in ‘I am, I exist’ refers to; the part of you that really makes you you. Many philosophers have provided rich accounts of what the self ultimately is, including the soul, the mind, one special feature of the mind (such as consciousness), a mixture of all these elements, or perhaps a mere illusion.
The ‘Cogito’ – Descartes’ famous claim ‘I think, therefore I am’ is often referred to as the cogito. The name comes from the Latin rendering of this phrase, which is ‘cogito, ergo sum.’ Descartes held that one can always believe this proposition with certainty. We cannot doubt our own existence, so the cogito survives his exercise of intense doubt. The cogito appears several times in Descartes’ writings, and he often phrased it slightly differently each time. It appears in the Second Meditation as ‘I am, I exist.’
Certainty – When one believes something with certainty, one is maximally confident that it is true. A certainty is something that is beyond dispute or immune to doubt. Although this captures the basic idea, like many epistemological notions, clarifying precisely what the notion of certainty amounts to is an ongoing area of philosophical research.
Vice – A bad habit that we learn over time through instruction or instinct and that we develop through repetition. What makes the habit bad is that, once we have that habit, our tendency is to do the incorrect thing in certain types of situations. We may choose to do something entirely uncalled for in that situation, or we may act at the wrong time, in the wrong way, to the wrong degree, or with the wrong attitudes, or for the wrong reasons.
Relative Mean – The “Goldilocks amount” of some type of action or emotion. When you act in this way, according to Aristotle, you act exactly as is required under the current circumstances. This means that you do what is called for by the situation at hand, rather than doing something too extreme or not doing something extreme enough. You do something in the moderate amount (the mean amount) relative to the specific situation you are in when you need to act.
Excellence/Virtue – A good habit that we learn over time through instruction and repetition. What makes the habit good is that, once we have that habit, we have a strong tendency to do the right thing at the right time, in the right way, to the right degree, with the right attitudes, whenever we are confronted with a situation that we know calls us to exercise that habit.
Doxastic Voluntarism – the view that we have at least some control over what we believe.
Evidence – information that increases the probability that a claim is true.
Sufficient – enough of something for a particular purpose. Whether something is sufficient is context-dependent.
Solon – In the Histories of Herodotus, Solon visits Croesus, the king of Lydia. Even though Croesus shows Solon all of his wealth, Solon refuses to call him the happiest man who ever lived because he does not know how Croesus will die
Priam – According to Greek mythology, Priam was the final king of Troy during the Trojan War. Despite his wealth and political power, he was killed by Achilles’ son Neopotolemus during the Sack of Troy
Virtue – The consistent and reliable tendency to perform one’s function excellently. When a person has a certain virtue, like courage, they have spent time developing the habit, in this case reacting to danger well, using their human abilities. The virtues then make it possible for us to live a life of flourishing
Sardanapalus – An Assyrian king described by the historian Diodorus as living a life of extreme decadence. Sardanapalus indulged himself with food, alcohol, and many concubines, even going so far to say that physical gratification is the purpose of life. Chrysippus said that, on his tomb is inscribed the following: “Though knowing full well that thou art but mortal, indulge thy desire, find joy in thy feasts. Dead, thou shalt have no delight […] I have only what I have eaten, what wantonness I have committed, what joys I received through passion; but my many rich possessions are now utterly dissolved.”
Function – the characteristic activity of a given thing which makes it what it is. The function of a knife is cutting, while the function of a heart is to pump blood
Eudaimonia – Frequently translated as ‘happiness’, eudaimonia means the attainment of active human flourishing, and is the end Aristotle identifies as humanity’s highest final good
Final Good – A good that we pursue for its own sake. Common examples of final goods include happiness, knowledge, and friendship
Instrumental Good – A good that we pursue for the sake of some other good. A common example is money, as money allows us to purchase other kinds of goods
Anytus – an Athenian politician, war general, and one of the primary accusers behind Socrates’ prosecution. Anytus feared that Socrates would undermine the young Athenian democracy he had helped create and defend
Oracle of Delphi – the high priestess at the temple at Delphi, the oracle was one of the most sought after seers of the ancient world and was thought to relay messages from the god Apollo
Chaerephon – an ancient Greek from the city Sphettus, Chaerephon is remembered as a loyal friend of Socrates, also making an appearance in two other Platonic dialogues, the Charmides and the Gorgias
Meletus – A poet and citizen of Athens and one of Socrates’ accusers. Amongst other things, Meletus accused Socrates of corrupting the youth
Apollo – the ancient sacred site Delphi was dedicated to the god Apollo, an ancient Greek god and the god that Socrates refers to throughout the Apology
Virtue – a character trait, acquired through habitual practice, that enables one to act well. The virtues can also be thought of as excellences of human character, as they make it possible for us to live a life of flourishing. Examples of the virtues include courage, prudence, and justice
The Evil Demon Argument – Argues that we cannot hold any of our beliefs with certainty because we could be radically deceived by an evil demon. A classic argument given by Descartes for doubting the reliability of almost all of our beliefs
Philosophical Skepticism – The position that we do not know many things that we ordinarily take ourselves to know
A Posteriori Knowledge – Knowledge that can only be acquired through having particular, concrete experiences. Such knowledge can be gained simply through our everyday experiences, or through more complex means like controlled scientific experiments
A Priori Knowledge – Knowledge that can be gained without having any particular concrete experiences. Such knowledge is typically gained by rational insight or intuition
Cartesian Method of Doubt – A process employed by René Descartes of rejecting all beliefs that he had at least some reason to doubt in order to see if he had any beliefs that he could know with certainty
Revelation – Theological truths that have been made known by means of some religious text, testimony, authority, or experience, or the act or process in which such truths are made known.
Rationalism – The view that the only reliable means of coming to know truths about God is reason. As a result, what we might otherwise believe by means of faith ought to be disregarded or even rejected in favor of what we must believe by means of reason.
Fideism – The view that the only reliable means of coming to know truths about God is faith. As a result, what we might otherwise believe by means of reason ought to be disregarded or even rejected in favor of what we must believe by means of faith.
Faith – The act of accepting a proposition as true for which there is less than demonstrable evidence, which rises above mere opinion but falls short of logical or scientific demonstration. Faith can also refer to a particular religious tradition or the body of beliefs that are central to that religious tradition.
Virtue – a character trait, acquired through habitual practice, that enables one to act well. The virtues can also be thought of as excellences of human character, as they make it possible for us to live a life of flourishing. Examples of the virtues include courage, prudence, and justice
Socratic Ignorance – an awareness of one’s own ignorance, and the reason that Socrates was deemed wise by the Oracle of Delphi. A person who lacks Socratic Ignorance may believe they know many things they actually don’t, leading them to overestimate how well they understand the world
Apology – a formal defense of justification of an action or belief. A Christian apologist, for example, is someone who defends their faith and seeks to justify it through an appeal to reason.
