# Stage Six- Introduction to Deduction

## Logical Form - sentences

The logical form of a sentence is its structure, without reference to its content (what it is about).

Logical structure is composed of two parts - variables for sentences (p, q, r), and logical connectives (not, and, or, if-then).

Start by identifying all logical connectives in a sentence. The parts that are left are assigned variables.

## Logical form - arguments

Modus Ponens: If P, then Q. P, therefore Q.

Modus Tollens: If P, then Q. Not Q, therefore not P.

Disjunctive Syllogism: P or Q. Not P, therefore, Q.

Hypothetical Syllogism: If P, then Q. If Q, then R. Therefore, if P, then R.

Dilemma: P or Q. If P, then R. If Q, then R. Therefore, R.

## examples

Example #1 (0:00) - sentence translation (easy)

Example #2 (2:07) - sentence translation (medium)

Example #3 (3:25) - sentence translation (hard)

Example #4 (5:27) - argument translation