Laws of Logic (Detachment and Syllogism)

Front

What is the Law of Detachment?

Back

The Law of Detachment states that if a conditional statement is true and its hypothesis is true, then the conclusion is also true.

Front

What is the Law of Syllogism?

Back

The Law of Syllogism states that if 'If P, then Q' is true and 'If Q, then R' is true, then 'If P, then R' is also true.

Front

Provide an example of the Law of Detachment.

Back

If it rains, then the ground will be wet. It is raining. Therefore, the ground is wet.

Front

Provide an example of the Law of Syllogism.

Back

If it is snowing, then school is canceled. If school is canceled, then there is no test. Therefore, if it is snowing, then there is no test.

Tags

CCSS.L.11-12.6

CCSS.L.8.6

CCSS.L.9-10.6

CCSS.W.11-12.2D

CCSS.W.9-10.2D

Front

What does it mean for a statement to be valid in logic?

Back

A statement is valid in logic if the conclusion logically follows from the premises.

Front

What is a conditional statement?

Back

A conditional statement is an if-then statement that expresses a relationship between two propositions.

Tags

CCSS.RI.8.1

CCSS.RI.8.8

CCSS.RL.11-12.1

CCSS.RL.8.1

CCSS.RL.9-10.1

Front

What is the hypothesis in a conditional statement?

Back

The hypothesis is the part of the conditional statement that follows 'if'.

Front

What is the conclusion in a conditional statement?

Back

The conclusion is the part of the conditional statement that follows 'then'.

Tags

CCSS.L.2.1F

CCSS.L.8.1C

CCSS.L.8.3A

Front

What is an example of a false conclusion using the Law of Detachment?

Back

If it is sunny, then I will go to the beach. It is sunny. Therefore, I will go to the beach. (False if the person has other plans.)

Front

What is the contrapositive of a conditional statement?

Back

The contrapositive of 'If P, then Q' is 'If not Q, then not P'.