From Peter Kreeft’s Socratic Logic:
There are three kinds of thoughts, or three acts of the mind:
- Simple apprehension [understanding a simple term—e.g., “man”]
- Judging [relating two concepts by predicating one term of the other—e.g., “man is mortal”]
- Reasoning [relating two or more judgments with a conclusion—e.g., “man is mortal; I’m a man; therefore I’m mortal”]
These three acts of the mind result in three mental products:
- Concepts (the products of conceiving)
- Judgments (the products of judging)
- Arguments (the products of reasoning, or arguing)
Expressed logically these are called:
- Terms
- Propositions
- Arguments (most commonly, syllogisms)
These logical entities answer the three most fundamental questions:
- A term answers what something is.
- A proposition answers whether something is.
- An argument answers why it is.
These logical entities also reveal three aspects of reality:
- Terms reveal essences (what something is).
- Propositions reveal existence (whether something is).
- Arguments reveal causes (why something is).
These logical entities can be judged logically good or logically bad:
- Terms are either clear or unclear (=ambiguous).
- Propositions are either true or false.
- Arguments are either valid or invalid.
To make a convincing argument you have to fulfill all three of the following conditions:
- Your terms are clear.
- Your premises are true.
- Your logic is valid.
If you want to critique someone’s argument, you have to show an error in just one of the following:
- They are using a term ambiguously.
- They are using a false premise.
- They are committing a logical fallacy (i.e., the argument is invalid; the conclusion does not follow from the premises).