1. -- in other words, logic is
i.e. the study of argument
and the use of reason
-- in other words, logic is
the study of thinking

2. Logic:
differs from Psychology
does not deal with all
mental phenomena (learning,
remembering, daydreaming,
etc.), but only with that type
of thinking called “reasoning.”

3. Logic
is not concerned with
emotional states at all, or
with the “inner processes”
going on in the mind of the
thinker.

4. Logic
is concerned only with
reasoning itself, and the
formulation of rules that will
help us determine if any
particular piece of reasoning
is logical; i.e. coherent and
consistent.

5. The Structure of Argument
The basic unit of logic is the
proposition or statement,
typically expressed in a
declarative sentence:
e.g. “Smith loves Jones.”
“Socrates is mortal.”

6. The Structure of Argument
The key characteristic of each
proposition is that it can be
either true or false, but not
both.
e.g. Either “Socrates is a man”
is true, or “Socrates is not a
man” is true -- but not both.

7. The Structure of Argument
The chief concern of logic is
how the truth of some
propositions (premises) is
connected with the truth of
another (the conclusion).

8. The Structure of Argument
For example:
All men are mortal. (premise)
Socrates is a man. (premise)
Socrates is mortal. (conclusion)

9. The Structure of Argument
The pattern of logic that lets
us connect these premises to
arrive at the conclusion we
call an inference.

10. The Structure of Argument
Without this pattern of
inference, we have merely a
collection of disjointed
propositions.
e.g.
“My dog has fleas.”
“The moon is made of cheese.”
“Strawberries are red.”

11. The Structure of Argument
Our primary concern is to
evaluate the reliability of
inferences, the patterns of
reasoning that lead from
premises to conclusion in a
valid argument.