  At one time, philosophers thought there was a quick and easy answer to these questions, an answer that immediately discredited moral claims. That answer was that in psychology and biology our justifications can and do ultimately ground out in empirical observations, whereas nothing of the kind is available for moral theory. If true, this would explain in a sharp way why psychology and biology might have a real claim on our opinions while morality and alchemy and various crackpot theories do not. The former can be tested against experience and pass the test, while the latter, while testable, can be seen to fail utterly.