LR Question Help

[Dionysus0]

Off of Preptest 22 Section 4 Question 21

Someone help me understand the credited answer, it feels like I am reading Being and Time.
Thanks in advance.

Terry: Some actions considered to be bad by our society have favorable consequences. But an action is good only if it has favorable consequences. So, some actions considered to be bad by or society are actually good.

Pat: I agree with your conclusion, but not with the reasons you give for it. Some good actions actually do not have favorable consequences. But no actions considered to be bad by our society have favorable consequences, so your conclusion, that some actions our society considers bad are actually, still holds.

Which one of the following correctly describes both an error in Terry's reasoning and an error in Pat's reasoning?

Credited Answer:

D) presupposing that if an action's having a certain property is necessary for its being certain type of action, then having that property is sufficient for being that type of action.

[luke]

Terry: Some actions considered to be bad by our society have favorable consequences. But an action is good only if it has favorable consequences. So, some actions considered to be bad by or society are actually good.

Pat: I agree with your conclusion, but not with the reasons you give for it. Some good actions actually do not have favorable consequences. But no actions considered to be bad by our society have favorable consequences, so your conclusion, that some actions our society considers bad are actually, still holds.

Which one of the following correctly describes both an error in Terry's reasoning and an error in Pat's reasoning?

Credited Answer:

D) presupposing that if an action's having a certain property is necessary for its being certain type of action, then having that property is sufficient for being that type of action.

you know they both make the same kind of fallacy so, to save time, you only need look at terry's flaw to get tcr.

terry:

p1. favorable consequence is necessary for a good action
p2. some actions deemed bad have favorable consequences
c.  therefore, some actions deemed bad are in fact good

this is a mistake. it confuses a necessary condition (only if) for a sufficient condition (if): just because an action needs to have favorable consequences in order to be good doesn't mean that favorable consequences are enough for an action to be good.

by analogy:

all soccer balls are spherical doesn't imply that everything spherical is a soccer ball.

[Dionysus0]

Thanks Luke, I understand it now.