This post seems to say I should look in the mirror to get my answer

I'd agree with that. However, I doubt Eliezer would agree that you should only look in the mirror. Perhaps we can steel-man the concept: Look in the mirror, holding up the evidence you've gone out into the world to collect. At that point, if you see two pieces of paper with possible answers to your question float by, it will be you who chooses which answer is better. Even if one of the pieces of paper just says "Do whatever your parents tell you to", it would still be you who chose to listen to that piece of paper rather than another one. (Eliezer makes this analogy somewhere (and he does a better job than I did), but I couldn't find it; otherwise, I would have cited it.)