The path not trodden...

So, I've been frustrated by a trend in some of the responses to different philosophical writing that I've read (for my philosophy class). There's an unquestioned dismissal--"the path not trodden"--that occurs when evaluating some points. I have three examples of this: Socrates' dialogue with Euthyphro, Bennett's commentary on Jonathan Edwards, and Fodor's rejection of dualism. For all three, a belief is simply said to be false: Euthyphro and Socrates dismiss the idea that things are good because God says they are; Bennett purports that Jonathan Edwards' view of human nature (total depravity) is 'bad morality'; and the rejection of dualism on the basis that there are no other examples of nonphysical things causing physical things, and therefore the position is not tenable.

I want explanations for why these things have been rejected, because I'm not ready to put any of them in the garbage. The impression that I get is that every philosopher we have read has presupposed their falsehood; therefore, the result of every philosopher is that those things are in fact false.

Now I'm tired. Tired. Tired.