4.1.4.2. Modus Tollens

Try these first

1. 1.

   Write down the structure of Modus Tollens using letters.

   Hint

   Remember the key components are a condition and the negation of the result.

2. 2.

   Identify the conclusion from the argument: 'If it’s sunny (P), then we can go outside (Q). It’s not possible to go outside (¬Q). What can we infer about it being sunny (P)?

   Hint

   Consider what not being able to go outside implies about the weather.

3. 3.

   If P implies Q, and not Q is true, what can we conclude about P?

   • P is true
   • P is false
   • Q is true

   Hint

   Think about what the negation of Q signifies regarding P.

4. 4.

   True or False: Modus Tollens allows for deriving conclusions from positive conditions.

   • True
   • False

   Hint

   Focus on the structure of Modus Tollens.

5. 5.

   Create a complex argument using Modus Tollens and illustrate its validation step-by-step.

   Hint

   Draft the argument focusing on where the logic connects.

6. 6.

   Analyze and correct the fallacy: 'If the sun is shining (P), the car is warm (Q). The car is not warm (¬Q), therefore the sun is not shining (¬P).' Is this a valid conclusion?

   Hint

   Consider external conditions that could impact the premises.