The argument's conclusion is that "good actions are impossible," and the main evidence in support of that is the idea that, since we can't really foresee the consequences of an action, we can't tell if it's good or not. There is a logical leap here between knowing that an action is good, and the action itself being good. If E weren't true, and an action could be good without one knowing that it is good, then the fact that consequences can't be completely foreseen wouldn't keep an action from being good.

This is a confusing argument, I think, just because the same terms are repeated over and over. Basically, negating the assumption comes down to saying, "Who says that you have to know that an action is good in order for it to be good?"

I didnt see that difference between knowing that an action is good, and the action itself being good

Thanks for the explanation.

I am not clear as to why 'E' is the answer. Could you explain it again please?