Peter Kreeft, in Socratic Logic, pp. 2-3:
On the basis of over 40 years of full time college teaching of almost 20,000 students at 20 different schools, I am convinced that one of the reasons for the steep decline in students’ reading abilities is the decline in the teaching of traditional logic.
Mortimer Adler’s classic How to Read a Book is based on the traditional common-sense logic of the “three acts of the mind” [simple apprehension, judging, reasoning]. . . . If I were a college president, I would require every incoming freshman to read Adler’s book and pass a test on it before taking other courses.
. . . . [C]lear writing and thinking are a “package deal”: the presence or absence of either one brings the presence or absence of the other. Muddled writings fosters muddled thinking, and muddled thinking fosters muddled writing. Clear writing fosters clear thinking, and clear thinking fosters clear writing. . . .
There is nothing more effective than traditional logic in training you to be a clear, effective, and careful writer.
C.S. Lewis’s last interview was on May 7, 1963—six months before he died. One of Sherwood Wirt’s questions was on writing: “How would you suggest a young Christian writer go about developing a style?”
The way for a person to develop a style is (a) to know exactly what he wants to say, and (b) to be sure he is saying exactly that.
The reader, we must remember, does not start by knowing what we mean. If our words are ambiguous, our meaning will escape him.
I sometimes think that writing is like driving sheep down a road. If there is any gate open to the left or the right the reader will most certainly go into it.
(“Cross-Examination,” in C.S. Lewis: Essay Collection and Other Short Pieces, ed. Lesley Walmsley, p. 555)
Seven years earlier (June 26, 1956), Lewis responded to letter from an American girl named Joan with advice on writing. Each of the five points is well worth considering, but none more so than the first one:
Always try to use the language so as to make quite clear what you mean and make sure your sentence couldn’t mean anything else.
(C.S. Lewis, Letters to Children, p. 64)
But in order to say what you mean you have to know what you are saying. What follows are a few notes from Peter Kreeft’s Socratic Logic (pp. 28-33) that can help to clear some of the cobwebs from the attic of your mind:
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:
- 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).