In responding to a prompt for my class, I gave the following argument:
- If moral subjectivism is true, then everyone is infallible about moral beliefs.
- Not everyone is infallible about moral beliefs.
- .’. Moral subjectivism is not true.
Over the course of my undergraduate career, I’ve come across many people who have espoused moral subjectivity. They basically say, “X is wrong because that’s what I believe.” If morality is subjective, that is, it is based on the individual, then it is entirely dependent on what the individual says. The truth value of “X is wrong/right” would be derived from the individual’s saying it. This almost seems like a moral subjectivist of this kind is infallible. How? Well, if my saying or believing “X is wrong/right” makes it the case that “X is wrong/right,” then that leaves out any opportunity of me being wrong about that statement. Let P = “eating humans is morally ok”. If I say that P is true, then the truth value is of that is given by my believing or saying that it’s the case. Whatever I say goes, and there can never be room for wrong. Russ Shafer-Landau puts it this way, “If morality is in the eye of the beholder, then everyone is seeing things equally well.” Hence, I am infallible. Premise one is in the bag.
But I don’t think everyone is infallible. Here’s why: We can change our minds. At one point, in this hypothetical situation, I said “eating humans is morally ok.” But suppose I change my mind to believe the statement ~P, that is, “it is not the case that eating humans is morally ok.” That presumes that I was wrong at one point in believing that P was true. But couldn’t the subjectivist retort that this doesn’t follow? They could say that believing ~P now just shows that morality changes since the claim is being made at a later point in time. The truth value of P simply changes, and they retain their infalibility. It seems this line of thought cannot work. But even without the argument, I think I can make an appeal to intuition here. It’s simply obvious that we can be wrong about moral beliefs. It’s possible that I can be wrong about my beliefs. I think this can be highlighted by the fact that there is moral disagreement. If you have two people who are making opposite truth claims, and both are moral subjectivists, they cannot both be right. So if Johnny says that P, and Sue says ~P, according to moral subejctivism, they are both right! But that means (P&~P) would be true, but that’s blatantly absurd. Moreover, there cannot be reason for the two subjectivists to disagree. Thus, in addition to the obviousness of P2, I’ve argued that at least one person, out of the two subjectivists who argue opposite truth claims, must be wrong. Hence, one cannot be infallible, and the premise that “not everyone is infallible about moral beliefs” is true. It follows by modus tollens that moral subjectivism is not true.
. Shafer-Landau, Russ. The Fundamentals of Ethics. New York: Oxford University Press, 2010.