Naturalism and Ethics
Why is it that certain actions are morally right, others morally wrong, and some morally neutral? Where does the demand of normativity come from? For much of the history of philosophy, the basis for ethics was grounded in non-natural entities. In fact, the kind of truths found in ethics seem inescapably non-natural. Below, I will show the basic problems for naturalism to give an account of ethics. If naturalism cannot provide an adequate basis for morality, then that counts strongly against the worldview of naturalism.
What is and is Not Under Discussion
From the outset I want to be clear that this argument has nothing to do with whether naturalists or non-naturalists are morally good or bad people. It's evidently clear that many naturalists are among the most morally commendable in society. Conversely, there are many people who believe in a non-natural basis for morality who act atrociously. The point here is not to figure out how these different groups act. Rather, the idea is to see whether philosophical naturalism provides a sufficient basis for morality. In other words, this is an issue primarily concerning meta-ethics, not practical ethics.
Ethics Naturalized
Philosophical naturalism is a theory that holds to a minimal ontology where all that exists must be physical/material or reducible in some way to physical/material substances. The challenge for naturalists is to explain how certain claims, like "Torturing babies for fun is morally wrong," are true on their account. What natural thing makes moral claims true? The answer naturalists give to this question, which I will discuss below, is woefully inadequate.
One attempt to naturalize ethics is to appeal to natural selection. According to this view, we believe moral claims as a result of natural selection. Why do we think killing innocent people is wrong? The defender of natural selection will say we believe this because societies where innocent people were killed without punishment didn't survive and pass on their genes. In order to survive, certain moral rules had to be adopted. Those communities and individuals who did not adopt these rules did not survive. So, in this way some naturalists try to show how natural selection would give a naturalized account of ethics.
The problem with this approach is that it doesn't give an account for why certain actions are morally right and wrong. This naturalist attempt only offers an explanation as to why we happen to think some things are right and wrong. This subtle distinction is crucially important in order to understand why this attempt to naturalize ethics fails. How would this type of naturalism handle, for example, the claim "murder is wrong"? The naturalist would explain that we believe and strive to follow this rule because our species has been psychologically programmed to believe it is true as a consequence of natural selection. But it is still unknown whether this moral claim is, in fact, true. After accepting this theory, one could ask oneself, "I understand why I happen to think murder is wrong, but is it really wrong? Is there any real restraint against me committing acts of murder?" And on the natural selection view, there is no reason to think any action is really right or wrong in the moral sense.
Here's another way to see the same criticism. If natural selection is supposed to provide the basis for moral right and wrong, then morality is founded upon an arbitrary foundation. Natural selection would explain the processes which have conditioned us to believe and behave in accordance with certain moral beliefs. Yet, if our moral framework is merely the by-product of mindless, impersonal conditioning, then it seems utterly arbitrary that we happen to believe these moral truths rather than any other. So, on this view, there is no reason to think that murder is wrong. We believe it is wrong merely because of the impersonal accidents of physical matter struggling to survive over time.
Many naturalists, aware of this sort of problem, take a different approach to naturalize ethics. They claim that ethics is not about cognitive claims that can be characterized as "true" or "false." Rather, moral claims are of a different type - moral claims only contain expressive meaning. This is called expressivism. On this view, moral claims express "pro" and "anti" feelings of the person making the claim. As such, these claims are not "true" or "false." To say, for example, that "murder is wrong" means "murder, boo!" or "murder yuck!" for expressivists.
This approach is favorable to naturalism because there is no need to speak about why moral claims are true or false. An expressivist can say that asking "why moral expressions are true or false?" is a category mistake. There is no need to give a basis for the truth-value of ethical normative claims because these aren't claims that can be classified as true or false.
Expressivism is all the rage in contemporary attempts to naturalize ethics. If successful, expressivism deflects the requirement to explain moral truths. The tug of moral rights and wrongs require no deeper metaphysical explanation than acknowledging that moral claims are expressions of people. What explains why moral expressions exist? The naturalist needs only to appeal to the existence of people who have these expressions.
One of the key problems for expressivism is that it denies an independent measure for moral claims by which we can assess the moral expressions of people. So if Jones says, "Torturing babies for fun is morally good," on what grounds can we say Jones is wrong? For Jones, if he happens to feel that this expression is correct, and the basis for a moral claim is in the agent's expression, the agent can never give an incorrect moral expression. There is no plausible "error theory" for moral claims, if expressivism is true. Every agent's moral expression would be correct, which would have devastating consequences. Some might say that we could appeal to the moral expressions of the majority of people in a society, but this won't help. By taking a survey of what most people feel about moral claims would not prove that Jones is making a wrong expression, it would (at best) show he is abnormal or that he has different tastes from most people. Since some people make erroneous moral claims, and expressivism cannot account for errors in moral claims, it follows that expressivism is wrong.
Another problem with expressivism follows from its denial of truth-values for moral claims. If moral claims lack truth-value, we should not be able to use them in logical proofs to infer conclusions since logic derives inferences on the grounds that claims are true or false. (In the philosophical literature this criticism is called the "Frege-Geach Problem.") Consider the following line of reasoning:
- It is wrong to torture babies for fun.
- Smith is a baby.
Therefore, - It is wrong to torture Smith for fun.
Premise (2) is a factual claim that has a true or false value, but (1), according to expressivists, is not. Since (1) is neither true nor false, one cannot logically derive the conclusion (3) from the principles of logic (try doing a truth-table with claims that are not true or false, and you'll see what I mean). The problem for expressivists is that a proof like the one given above is sound, and that their view cannot account for any moral reasoning of this sort.
Another problem with expressivism is that it is indistinguishable from relativism. Many expressivists try to resist relativism, but it is difficult to see any difference between expressivism and relativism. If the meaning of moral claims are grounded in the expressions of people, and people have different expressions, then it follows that expressivism entails relativism. Moral relativism, of course, is untenable. Unless expressivists can show how their view is different from relativism, they will not be able to avoid the same criticisms that show relativism is false.
Conclusion
Naturalists cannot account for the truth-value of moral claims. Attempts to naturalize the truth-claims by recourse to natural selection fail because moral "oughts" cannot be derived by explaining the psychological conditions that program them. Additionally, attempts by naturalists to show that moral claims have no truth-value fail as well. Thus, naturalism leaves the truth of moral claims inexplicable. For this reason, naturalism cannot account for the fundamental truths of ethics. Therefore, naturalism is an inadequate philosophical system.