Moral questions typically have an empirical component. For example, the question whether we have an obligation to paint all the roofs in the world white depends in part of the question whether doing this would reduce global warming, and that is an empirical question. And as Miranda Fricker points out, if utilitarianism is correct, then you can work out what is right across the board by answering the empirical question of what would generate the most happiness. But the question whether utilitarianism (or pretty much any other ethical theory) is correct does not seem to be an empirical question. What experiment would help? So while applying an ethical theory to determine what is right may depend on empirical evidence, testing and ethical theory does not seem to be an empirical matter. The empirical facts only seem to take us so far when it comes to determining what we ought to do.

The most compelling reason not to eat meat is not because it involves killing animals but because it so often involves causing animals to suffer, especially in factory farming. From this point of view there might be nothing wrong with eating free range chicken (because their lives are not miserable) or shrimp (if they are incapable of feeling pain). But as Peter Singer argues, causing unecessary suffering seems wrong. If some factory farming were the only way for some people to get enough iron, then it might be a tough call. But I doubt it is, and if I am wrong about this the argument still applies to many of us who do have easy alternatives. And causing unecessary suffering seems wrong even if the perpetrators are acting perfectly naturally.

Best for whom? The enviroment may change so that a particular species of tree is no longer very successful at propagating itself. If we do nothing, it will go extinct. But it might be much better for us if we did not let that happen, because the bark of the tree contains a chemical that is highly beneficial to us.

Suppose I know that half the time the sea is calm, half the time it is very rough. If I send you out in a rowboat without checking the weather, my act is immoral, even though I am ignorant of the consequences. I would say that the case of someone who believes that God will protect his child from a road accident is different: it's error, not ignorance. Here the moral situation may be more subtle, since we may hesitate to blame people who are acting sincerely on the basis on their beliefs, even if we are convinced that their beliefs are incorrect. But I'm inclined to say that there can be cases where there is a kind of willful ignoring of the evidence that leads to moral culpability.

How can there be a right to consent without a right to refuse? The problem here is conceptual, not moral.

I take it that the Euthyphro dilemma against divine command theory involves the choice between saying that something is right because God says it is right and saying that God says something is right because it is right. The former claim seems false, since it seems to entail the falsehood that if God simply said torturing kittens was right, that would make it right to torture kittens. And the latter claim does not seem strong enough for divine command theory, since it does not make God's command the source of moral value. I'm no expert on this topic, but there seem to be two obvious rejoinders. One would be to bite the bullet and allow that God is the source of morality, so the first horn of the dilemma is correct. If God commanded kitten torture, then that would in fact be the right thing to do. Our strong initial intuition to the contrary is just due to the fact that we have been brought up on the basis of what God actually commands, which (let's suppose) includes a command to be kind to animals....

Racist laws and laws concerning slaves provide examples of how legality and morality come apart. A law could make it legal to keep slaves, even if that is immoral; a law could prohibit one from helping someone of another race, even if that is morally obligatory. You can fail to do what is right without breaking any law, and breaking a law may not be immoral.

I think that 'decide' can mean two different things here. It can mean who creates the standard of good people and bad people. Or it can just mean who is a good judge of who is good and who is bad. My own view is that nobody creates the standard: what makes somebody good is what they do, not whether someone (even God) says they are good. But some people may be good at judging who is good and who is bad, though how we can tell who those people are is a tough question.

I'm inclined to agree with you that someone who does the right thing because it is the right thing is morally more impressive than someone does the right thing for the sake of some reward. At the same time, you can believe in God (and even believe in heaven), do the right thing, yet not do it for the sake a reward, but just because it is the right thing.

The main way we cause pain to aminals is through the way we raise them in factory farms, so even if plants could feel pain (though like Richard, I bet they don't), we might be able to grow and harvest them without causing them any more pain than, say, we cause a free-range chicken. But if forcing them to grow in those straight rows causes them severe and prolonged distress....