One can never tell whether another person is acting from an ulterior

EXPLANATION FROM Fox LSAT

There’s a gap between the first clause and the second clause. Listen: “One can never tell whether another person is acting from an ulterior motive, therefore it is impossible to tell whether someone’s action is moral.” Really? Why would you reach that conclusion? Isn’t there a gap there? What do ulterior motives have to do with morality? The speaker has assumed, necessarily, that being able to tell whether someone’s action is moral requires that we be able to tell whether that person acted from an ulterior motive. Without that, the logic just can’t make sense. But if we assume that, the argument makes more sense: “So one should evaluate the consequences of an action rather than its morality.” Okay, I guess that follows. If we can’t tell whether something is moral, then we certainly shouldn’t try to evaluate its morality.

A) This is another way of saying, “We can’t tell whether an action is moral unless we know the motives behind it.” This is an assumption of the argument, so making it explicit strengthens the argument.

B) Where did “assigning praise and blame” and “most important” come from? This isn’t close.

C) Wait a minute. If we can sometimes know our own motives, then wouldn't we sometimes be able to evaluate the morality of some (our own) actions? This answer would actually weaken the argument, so it's out.

D) The argument is not, in the slightest, about whether actions are “good” or “bad” or whether people can be “good” or “bad.” Like B, this is nowhere close to the correct answer.

E) This answer says, “If we don’t know the consequences, we can’t know the morality.” So what? Evaluating consequences was suggested as an alternative to evaluating morality. One has nothing to do with another. This answer choice just takes terms from the argument, spins them in a food processor, and dumps out a bunch of garbage.

The best answer is A.