Helen De Cruz recently floated the idea that if our moral beliefs are produced by evolution, they are unlikely to be objectively true. “The prospects for an evolutionary-informed moral objectivism are grim, for here we stumble on the problem of the familiar Humean is/ought gap. . . It seems then that as we offer a plausible causal story of moral norms, we will be unable to make mind-independent moral truths figure in the explanation.”
Here I offer three arguments to counter what Helen calls “evolutionary debunking arguments” against moral objectivism.
Argument 1: The Irrelevance of Evolution Suppose that we have some moral beliefs by natural selection. What are they? Well, here is a belief that is not among them:
P: When at the edge of a precipice, you are in danger.
Most people believe P, and it has been shown that even infants recoil from virtual cliffs, so believing P is not a matter of learning. Belief in P is (let’s stipulate without further ado) produced by evolution. But P is not a moral belief. It has no moral content whatsoever. Similarly, “I should eat when I am hungry” is not a moral belief, though it is a product of evolution.
When people talk about moral beliefs produced by evolution, they give examples like:
R: Repay kindness
Or “Help those in dire need.” Concede that R is (more or less) universally held, but (like P) not learned—hence selected for (perhaps by reciprocal altruism). The question is: does this imply that R is not objectively true? Allowing the approximate and the ceteris paribus as truth, surely there is a presumption in favour of R qua belief that has survived natural selection.
Argument 2: The Social Content of Morality Argument 1 is unsatisfying. Evolutionary debunkers make a content-specific claim about natural selection and objective morality. Argument 1 relies on a content-neutral presumption.
Here is a plausible claim about the content of morality.
Altruism: Many (if not all) moral judgements are about the rightness of doing good for others to the subject’s own detriment.
Altruism is the traditional problem for evolutionary ethics. How can natural selection encourage behavioural tendencies that are to the subject’s detriment?
This traditional problem has traditional answers. Group selection is one. Mutually supportive groups demand altruism, but individuals that belong to such groups are fitter on average than those that do not. But these groups are unstable. They can be infiltrated by freeloaders who take advantage of their "unselfish" brethren. True, but mutually supportive groups will also evolve disincentives against freeloading. Some freeloading inevitably escapes the net of these disincentives, and so we end up with the messy situations that we observe every day. Lots of moral behaviour, some renegade behaviour.
Group selection is a laboratory in which group benefiting behaviour is tested. The end product is optimally altruistic behaviour. Such behaviour is often other-regarding and self-detrimental. Beliefs based on optimal altruism are candidate moral beliefs, and their truth is relevant to their evolutionary success.
This is the traditional defence of evolutionary ethics. It also appeals to kin selection, reciprocal altruism, and so on.
Argument 3: Supererogation Group selection and associated devices are a start, but they cannot explain real morality. Why not? Well look around you. Many people will take a risk to save others from harm; many will give to the needy; most are honest in transactions with friends. But morality requires much, much more. It requires that you risk death to save a child being sold into prostitution; that you give 30% of your mean-exceeding income to charity; that you are honest in dealings with government. Group selection cannot explain these extremes, and if it did, it would be immediately refuted, since most people don’t go to the extremes that morality demands. The scope and intensity of morality vastly out-extends the scope of kin selection, reciprocal altruism, and group selection.
Let me gesture to a strategy for defending supererogation. Natural selection produces certain behavioural tendencies. Reciprocal altruism may be one of them. But this is not all that there is to belief. R might be a first step from reciprocally altruistic behaviour, but natural selection has also endowed us with truth-apt belief-checkers. Beliefs formed on the basis of behavioural tendencies come under rational examination, using methods that are also provided by natural selection. We do not stop at R.
The principle of sufficient reason is an essential component of rational cognition. It pushes beliefs like R from the timorous other-regard of reciprocal altruism to the heroic heights of Singerian morality. Evolution makes you do good to your kin and to those who have been good to you in the past. But the principle of sufficient reason leads to further questions: Why just kin? Why just benefactors? These questions lead to more extensive beliefs and thus to the moral ideal. Do good to all. Turn the other cheek. Cognitive romantics like Jesus and Gandhi lived by these beliefs. Societies in collapse forsake them altogether.
The discovery of morality is a joint project of the Social Human and the Enquiring Human, both products of natural selection. Admittedly, cultural evolution has played a role as well. And this has been a Sisyphean tale: Socrates meets Thrasymachus; Kant encounters Nietzsche, Gandhi stands across from General Dyer. Nevertheless, belief has its own evolutionary dynamic. The evolution of moral belief is different from the evolution of moral behaviour.