The author uses the word "immediacy" (line 39) most likely in order to express

on February 7, 2020

Flawed Contrapositive argument

For question 8, i got the right answer but i identified the flaw as being that the passage and option D both invoked the necessary condition of the contrapositive to conclude the sufficient of the contrapositive, making it a flawed contrapositive argument. Is this way of doing it wrong?

1 Reply

Skylar on February 8, 2020

@KatrinaMusa, happy to help.

Your understanding is valid.

The passage states: PL -> OPTC. It then takes the existence of NOT PL to incorrectly conclude NOT OPTC.

This is illustrated as:
- - - - - - - -

The video explains this flaw as only negating the original principle. It says that you cannot just negate the principle PL -> OPTC to get NOT PL -> NOT OPTC.

You explain it through the lens of the contrapositive. This means that, from the contrapositive NOT OPTC -> NOT PL, you cannot take the N condition (NOT PL) to conclude the S condition (NOT OPTC).

Both explanations identify the same error but explain them from different perspectives (that of the original principle versus that of the contrapositive). Nevertheless, both ways are correct and should lead to the same answer.

Does that make sense? Please let us know if you have any other questions!