Socratic Logic - Judgement

The following are the notes I have taken from Peter Kreeft's wonderful Socratic Logic textbook. I highly recommend you buy it. This is a book which deals with classical logic (as opposed to modern symbolic logic.) It is easily the best overall book on logic I have ever read and one of the few I have that are worth making notes from. I even have a small duotang with these notes in it I can carry around and reference on a regular basis.

Propositions

Judgement is the second act of the mind, and deals with propositions.  Propositions are expressed in declarative sentences.

With judgement we are concerned about the truth or falsity of a proposition.

What is Truth?

Truth is one of the easiest concepts in the world.  The following two definitions (which basically say the same thing) are commonsensical.

Truth is the property of assertions (propositions) that corresponds with reality.  (Ravi Zacharias)

If a man says of what is that it is, or what is not that it is not, he speaks the truth.  But if he says of what is not that it is, or of what is that it is not, he does not speak the truth. (Aristotle)

Subject and Predicate Terms

A. Subject term - what we are talking about.

B. Predicate term - what we are saying about the subject.

Kinds of Propositions

A. Less than sentences (terms)

B. Sentences

1. Declarative Sentences (Propositions)

 

a. Categorical (Simple)

i. Universal affirmative

ii. Universal negative

iii. Particular affirmative

iv. Particular negative

b. Compound

i. Hypothetical

ii. Disjunctive

iii. Conjunctive

2. Non-declarative sentences

 

i. Imperative

ii. Interrogative

iii. Exclamatory

iv. Performative