Deductive Reasoning

Wednesday, February 11, 2009

In Philosophy class today, we learned three types of deductive logic:

1. Syllogism
2. Modus Ponens
3. Modus Tollens

Syllogism is a deductive reasoning where a major premise (which contains A term and B term) and minor premise (which contains B term and C term) combine to make a conclusion (which contains A term and C term).

An example of Syllogism would be:

Humans are not perfect.

Kobe is a human.

Kobe is not perfect

Modus Ponens is a deductive reasoning where a "if p, then q" statement is given and "p" is given as a positive premise, so that we may be sure of the positive premise of "q".

An example of Modus Ponens would be:

If he goes to work, then he will be paid.

He went to work.

Therefore, he was paid.

Modus Tollens is a deductive reasoning where "if p, then q" statement is given and "q" is given as a negative premise, so that we may be sure of the negative premise of "p"

An example of Modus Tollens would be :

If she studies for the exam, then she will ace the exam.

She did not ace the exam.

Therefore, she did not study for the exam.