Top Law Schools

I guess I just cannot get assumption question right.... can anyone explain me why? I actually eliminated D at first glance, choosing between C and E. Eliminated C eventually because think "harm others" is wrong. Thought E would be right... but apparently, I was wrong.

Please help!

Good question, LSAC!

The conclusion of the argument is that only people who don't realize what will happen (consequences of their actions) would act immorally. Or, to switch it up, if you have acted immorally, you must not realize what the consequences will be. Why? Because completing an immoral act will eventually hurt yourself.

The premise about immoral acts hurting other people is not part of the core of this argument. The conclusion's additional note that it's not a character defect is also not relevant to the core (the premise(s) that support the conclusion).

The argument is assuming that one would not want to do something that hurts oneself. What if you're willing to undergo some suffering in order to see others hurt (or gain one of the other many boons of an immoral act)? (D) fills this gap by noting that those who do act immorally do NOT want to harm themselves. If we negate (D), the argument does not make sense: why would we conclude that a wrong-doer must not understand the consequences if he or she intends those consequences. Negating assumptions is an important test -- correct assumptions, when negated, should destroy the argument (this is somewhat problematic if the assumption is sufficient, but not necessary, but that's usually rarely a problem).

As for the wrong answers:

(A) is out of scope -- the argument does not focus on responsibility
(B) is irrelevant to the core. (B) ties together harming others and oneself, a connection already established in the argument. This is basically a premise booster.
(C) is tempting. It begins promisingly - "Only someone with a character defect would..." - maybe this will say that only those folks would choose to harm themselves, so that would explain why the folks who act immorally and hurt themselves must be ignorant of what's going to happen. Instead, it focuses on harming others.
(E) is tempting as well. It's often useful to change up an "none" to make the statement positive (especially with a "lack" in there as well). Here it translates to "all who knowingly harm themselves have character defects. This ties together two possible explanations for acting immorally, and we need those separated for the argument to make sense (since the argument states that one is not the reason while the other is).

If you wanted to diagram the argument, the core of it is:

1. Immoral Actions --> Hurt Actor (meaning yourself)
2. Conclusion: Immoral Actions --> Ignorant

To have #1 lead to #2, you'd need Hurt Actor --> Ignorant, which (D) provides Hurt Actor --> Ignorant