Now, one might reasonably wonder how we can discover that we ourselves or members of our community have been following customs that are morally wrong if we are located in societies and communities that follow these customs. This is where moral theory, conceptual analysis, and argumentation come in. We can use moral theories to assess the norms, conventions, and practices of our own communities. Even so, it is difficult to understand how things might be different from within our own culture. This is where outside perspectives are particularly valuable.
As a number of philosophers who study the theory of knowledge have argued, the critical eye of people with very different beliefs, norms, and values to our own can be extremely useful for assessing the claims we endorse and the things we do. The idea is that if a claim or practice can withstand criticism from a wide variety of different perspectives with very different assumptions then it must be pretty good, or at least it is likely to be morally acceptable. It is rather like using a variety of different experiments to test the same hypothesis. If your hypothesis is confirmed using a wide array of very different experimental designs, then science has given you a good reason for thinking it is likely right. (Notice, that this process does not give us grounds for dogmatically asserting the absolute truth of our discovery in either science or ethics.) This assessment must be done in good faith. In the same way that if we value scientific knowledge we should welcome having multiple rigorous tests of our favored theories, if we want to do the right thing we should be open to criticism from a wide variety of different people whose views are very different from our own. Of course, others may or may not be right in their criticisms. Either way, being able to understand them and identify why they are right or wrong will give us insight into the ethical issues and better justification for our own ethical decisions.
Unfortunately, we often don’t have access to a variety of people from many different backgrounds to give us feedback on our ideas and activities. Even if we do, these folks may have better things to do than help us with our moral dilemmas. Fortunately, we do have access to published work by thinkers from around the globe and we can draw on this and our own imaginations to guess what those who disagree with us might say. This kind of dialogic reasoning—where one puts forward one’s own view, then comes up with objections to that view, and then responds to those objections—is characteristic of philosophical work (we will discuss this more in section II). If you want to do the right thing then sincerely considering arguments both for and against the various possible actions that are open to you is one of the best ways of ensuring that you do.
Now, it might reasonably be asked whether such a process of rational reflection, judgement, and action will always provide the right answer. Philosophers have disagreed on this point, at least in principle. However, the very fact of their disagreement suggests that, for practical purposes, all philosophers are going to have to admit that seemingly rational people do in fact disagree about moral issues and sometimes these disagreements are intractable.