Katarzyna Lazari-Radek and Peter Singer’s paper “The Objectivity of Ethics and the Unity of Practical Reason”, published in Ethics 123 (2012): 9-31, aims to defend the objectivity of ethics, or more precisely the objectivity of a particular ethical judgement, against the kind of evolutionary debunking argument that was brought forward especially by Sharon Street. They take as their starting point the “dualism of practical reason” that confounded Henry Sidgwick in his Methods of Ethics and that prevented him from concluding that there is only one rational answer to the question what we ought to do, namely the utilitarian one that favours impartiality and tells us to aim at the good of all. Sidgwick’s problem was that it seems just as rational to only aim at one’s own good. Thus practical reason commands us to both pursue our own best interest and the best interest of all. Although those two goals may often coincide, there are clearly also situations where they can clash. Therefore, in those situations, reason cannot tell us what we ought to do. Sidgwick thought that this problem could not be resolved and that, therefore, ethics cannot be completely rationalized. Lazari-Radek and Singer think it can.
Their strategy is to revisit Street’s evolutionary critique of objectivity in ethics and then to show that while the maxim of universal benevolence or impartiality survives the attack, rational egoism does not. Street has argued that our evaluative attitudes including our moral beliefs about what is right and wrong have been shaped by evolutionary forces and that because our knowledge of how evolution works gives us no reason to suppose that it favours the development of evaluative attitudes that are objectively true (rather than beliefs that are conducive to our survival and to reproductive success), it would be a very unlikely coincidence if our moral beliefs actually were all true. If we were constructed in a different way (say, more like social insects), so that our survival and reproductive success were dependent on different evaluative attitudes, then we would think differently about what is right and wrong. Hence, we have no reason to suppose that our moral beliefs are objectively true.
However, Lazari-Radek & Singer argue that while this argument is on the whole persuasive, it does not undermine the objective truth of the ultimate principle of ethics, which, with Sidgwick, they take to be the principle that we should always do “what is best for the well-being of all” (16), precisely because such a principle does not seem to improve our chances of survival or to increase our reproductive success. On the contrary, it seems to diminish it (19-21).
Indeed, if believing in the objective truth of that principle were conducive to our survival or reproductive success, then we would have no good reason to suppose that the principle was objectively true. But if it is in fact not conducive to our survival or well-being, then, paradoxically we do have a reason to regard the belief as objectively true. Why is that? Because if that belief does not stem from our evolved evaluative attitudes, then it can only be the result of the use of reason. Of course our ability to reason generally is very useful for us by allowing us to solve problems that would otherwise have threatened our survival, so it no doubt has evolutionary value, too, but it is quite possible that it also allows us to do things that are not relevant to our survival, like doing advanced physics and mathematics and grasping objective moral truths. So when we ask why we developed those particular abilities in the first place if they are not conducive to our survival, then a plausible explanation for their existence is “that the ability to reason comes as a package that could not be economically divided by evolutionary pressures. Either we have a capacity to reason that includes the capacity to do advanced physics and mathematics and to grasp objective moral truths, or we have a much more limited capacity to reason that lacks not only these abilities but others that confer an overriding evolutionary advantage. If reason is a unity of this kind, having the package would have been more conducive to survival and reproduction than not having it.” (17)
The unity of reason helps us explain why we have the ability to track moral truths despite the fact that we could survive and reproduce just as well, or even better, without it, and this lack of an evolutionary explanation allows us to conclude that the principle of universal benevolence must be objectively true: “there is no plausible explanation of this principle as the direct outcome of an evolutionary process, nor is there any other obvious non-truth-tracking explanation.” (26)
For the same reason we can now also conclude that practical egoism, i.e. the maxim that we should always choose the action that produces the best outcome for ourselves, is not objectively true. We do, after all, have a perfectly good evolutionary explanation for why we should have that particular evaluative attitude. The belief that we primarily ought to promote our own good and that of our kin rather than that of everyone is exactly the kind of evaluative attitude that we should expect to have developed under evolutionary pressures. It is therefore not reliable and should not be seen as having any normative significance. Since we have that attitude not because we have used our ability to reason and as a result grasped the truth of the underlying principle of egoism, but merely because we have been shaped by the forces of evolution to be that way, practical egoism is in fact not rational. Sidgwick’s dualism of practical reason is thus proven to be unfounded. There is no dualism of practical reason. What practical reason commands is one thing, and one thing only: that we always seek and promote the best outcome for all (28).
Is that argument convincing? I think not. While it may make sense to distrust beliefs and evaluative attitudes that we merely have because having them increases (or at one point did increase) our evolutionary fitness (so that we can assume we would also have them if they were not true) and to try and confirm them on independent grounds, this gives us no reason at all not to hold on to those beliefs and attitudes. It merely gives us reason to doubt that those attitudes are objectively true. If I have to have a healthy concern for my own good to survive, and I do have an interest in surviving, then it is perfectly rational for me to promote my own good first and foremost. It is just not rational to believe that this is what I ought to do, or more precisely that it is objectively true that this is what I ought to do. In other words, it is difficult to uphold moral realism in the face of an evolutionary explanation of our moral beliefs, but it is not difficult to continue letting ourselves be guided by certain moral or prudential principles.
Perhaps more importantly in the context of the present argument, the fact that we do not have an evolutionary explanation for some of our evaluative attitudes, e.g. universal benevolence or the belief that we should do what is best for all, does not imply that they are more reliable than those that can be thus explained. When Lazari-Radek and Singer state that “there is no plausible explanation of this principle as the direct outcome of an evolutionary process, nor is there any other obvious non-truth-tracking explanation” (26), they simply assume without further argument that those acts of reasoning that lead us (or some of us) to postulate that particular moral principle of universal benevolence are truth-tracking. But surely the fact that a belief is not directly caused by evolutionary forces does not prove that we have it because it is true. If reason comes indeed in one package, so that our ability to postulate the truth of that particular moral principle is a mere (not fitness-enhancing) by-product or our (generally fitness-enhancing) ability to reason, then we have already explained it. A further explanation – we have it because that belief is true – is not needed. Moreover, it is difficult to see why we should assume that, although reason is generally an ability that has evolved because it increases our chances of survival and not because it leads us to the truth, should in some instances allow us to see the world as it really is. If reason is not generally truth-tracking, why should we suppose that it is when it leads us to have beliefs that are not conducive to our survival? The hypothesis of a “unity of reason” helps us explain how we could have developed an ability to grasp objective moral truths, just as it helps us explain why we have developed the ability to grasp abstract mathematical truths that have no practical value, but it doesn’t do anything to show that we have indeed developed such an ability.