Every action has consequences and among the consequences of any action

Every A has Cs. And among those Cs there are secondary As. Because we don't know if those CAs WILL be good we cannot know if the initial A IS good. To know that A is good is therefore impossible.

Every action has consequences and among the consequences of any action are other actions. And knowing whether an action is good requires knowing whether its consequences are good, but we cannot know the future, so good actions are impossible.

Which of the following is an assumption on which the argument depends?


(A) Some actions have only other actions as consequences.
Well, the argument did say that among Cs are secondary As, so whether they are MANY or SOME doesn't destroy the argument either way.

(B) We can know that past actions were good.
Using the negation technique we get: We CANNOT know that past actions were good. Basically a similar or somewhat repeat of a statement in the argument about not knowing the future. This negation doesn't destroy the argument (the initial statement). It simply says adds another thing we don't know about.

(C) To know that an action is good requires knowing that refraining from performing it is bad.
Irrelevant, I daresay. But let's use negation - To know that an action is good requires NOT knowing that refraining from performing it is bad. Ok, let's suppose that latter statement is true, does that destroy the argument? Nope. The argument is saying that because we don't know the future we cannot know is something is good. We have to attack THAT line of reasoning.

(D) Only actions can be the consequences of other actions.
Even if something other than CAs occured it doesn't destroy the argument. This statement doesn't have to be true for the argument to hold. Suppose one of ten CAs had a neutral effect.

(E) For an action to be good we must be able to know that it is good.
Using the negation technique we get something like: For an action to be good we must NOT be able to know that it is good. This latter statement would destroy the argument. The argument literally says knowing whether an action is good requires knowing whether its consequences are good