The Argument from Analogy
In this passage, Aristotle uses an argument from analogy – Aristotle claims that, because two items are the same in one respect, they are the same in another. Aristotle thinks it is obvious that becoming healthy and strong requires doing things in the middle relative to the situation, and he thinks that becoming morally good is analogous, or relevantly similar, to becoming physically healthy and strong, so becoming morally good requires doing things in the middle relative to the situation. Let’s look at this argument in premise/conclusion form:
Premise 1: Strength and health are beneficial states of body that we develop through instruction and learning and then improve upon and preserve through practice and repetition.
Premise 2: Moral virtues are beneficial states of character that we develop through instruction and learning and then improve upon and preserve through practice and repetition.
Premise 3: Physical strength and health are the types of states that require consuming the fitting, or intermediate, amount of food in any situation (not eating too much or too little) and exercising an appropriate amount in any situation (not exercising too much or too little) to preserve and improve them.
Inductive Premise: The development of and improvement of any given state of the body, mind, or character is directly tied to the type of state that it is, such that states which develop and are preserved in similar ways are likely of the same type, at least as regards their preservation and improvement.
Conclusion: Therefore, it is likely that the moral virtues are the types of states that require acting in the fitting, or intermediate, amount in any situation (not doing too much or too little) and feeling emotion in the fitting amount in any situation (not feeling too much or too little) to preserve and improve them.
Arguments from analogy involve reasoning from things known to things unknown or uncertain, and so are not valid forms of reasoning, strictly speaking. However, some analogical arguments are better than others, and Aristotle’s inductive argument here relies on an implied premise, which says that the core features required for development and improvement of bodily states are likely of the same general type as those core features required for the development and improvement of mental states and states of moral character. If the inductive step is strong, then the argument from analogy will be strong too! Do we have reason to think that if two things are cultivated in similar fashion, then they likely have some core characteristic that explains the parallel development processes of both?