The way he phrased the question was "would you kill babies if it was the right thing to do?", but the intended meaning is the same.
Its a short sequence of posts, not all directly related to that question, 1 2 3 4 5 6
There may be others related to it that I missed, the sequences are long and I don't have time to trawl through them all.
Joshua Greene manages to squeeze his ideas about 'point and shoot morality vs. manual mode morality' into just 10 minutes. For those unfamiliar, his work is a neuroscientific approach to recommending that we shut up and multiply.
Greene's 10-minute video lecture.