Can Evolution Debunk our Moral Beliefs?
Evolutionary theory has been immensely successful in the biological sciences. No doubt this is an understatement. However, owing to this success, and the sheer beautiful simplicity of the fundamental idea (replication+mutation+competition=diversity), it has been applied to many more domains with varying degrees of success. One such domain is ethics, another is meta-ethics. The failed eugenics movement, with its grotesque conclusions, points us to its failure within ethics, but can the same be said of meta-ethics? Perhaps our belief in a stable, objective morality is a last vestige of pre-Darwinian “religiousism”, and philosophers should be looking to our evolutionary history in order to understand the status of moral claims.
Unfortunately, I think this faith that the facts of biological evolution can tell us anything interesting about meta-ethics, or at least make certain meta-ethical problems retractable, is misfounded. An entire survey of the literature is beyond the scope of this article, so I will focus on a quintessential case, Michael Ruse’s arguments in Moral Philosophy as Applied Science (1986). It’s my wager that the arguments I will present here against Ruse hold in any attempt to derive meta-ethical implications from the facts of our evolutionary history.
The evolutionary biologist Michael Ruse has argued that “human beings function better if they are deceived by their genes into thinking that there is a disinterested objective morality binding upon them, which all should obey” (Ruse, 178). He takes the Darwinian implications for meta-ethics to be something akin to an error-theory of morality. Human beings merely think there is some mind-independent moral law which prescribes their behavior, but in fact there is no such thing.
I will argue that while Ruse’s case fails because he attempts to derive a metaphysical conclusion from genealogical considerations, even though we may nevertheless find his argument compelling if framed in epistemological terms. Having done this, I will then show how we may nevertheless be confident in the justification of our moral beliefs regardless of the influence of evolutionary forces on the development of our moral faculties.
Ruse’s Metaphysical Argument
Ruse argues that our “sense of ‘right’ and the corresponding sense of ‘wrong’, feeling we take to be above individual desire and in some fashion outside biology, are in fact brought about by ultimately biological processes” (Ruse, 178). Ruse’s main thesis is that
We think morally because we are subject to appropriate epigenetic rules. These predispose us to think that certain courses of action are right and certain courses of action are wrong. (Ruse, p.180).
It should be noted that from the very outset Ruse seems to sneak in the very conclusion he’s trying to derive, that “objective morality” is an illusion hoisted upon us by our genes and evolutionary past. He writes that these epigenetic rules “give the illusion of objectivity to morality”, though nothing in his empirical case has shown anything of the sort. Ruse is trying to give an empirical account of why we come to believe in moral norms and obligations, and along the way this account will reveal that morality’s claim to “objectivity” is an illusion. But whether our beliefs are illusory is not determined by the empirical data. Once an empirical account of our predisposition to believe in the existence of a moral reality is provided then one can ask whether our beliefs accurately “map onto” or “track” the relevant phenomena in question.
According to Ruse “moral reasoning is likewise moulded and constrained by epigenetic rules” (Ruse, 183). As an example of this, Ruse cites the case of incest, “full sexual attraction and intercourse, and not merely exploratory play among children” (Ruse, 184), which he points out reduces the evolutionary fitness of the “inbred” offspring that might come out of such a union, as is well documented.
However, this biological effect of inbreeding is not widely known throughout societies, particularly those with little or no scientific knowledge of heredity. So what causes us to avoid incest initially is
a sensitive period between birth and approximately six years. When children this age are exposed to each other under conditions of close proximity…they are unable to form strong sexual bonds during adolescence or later. The inhibition persists even when the pairs are biologically unrelated and encouraged to marry. Such a circumstance occurred, for example when children from different families were raised together in Israeli kibbutzim and in Chinese households practising minor marriages (Ruse, 184).
The entire process is fleshed out by Ruse:
Lowered genetic fitness due to inbreeding led to the evolution of the juvenile sensitive period by means of natural selection; the inhibition experienced at sexual maturity led to prohibitions and cautionary myths against incest or (in many societies) merely a shared feeling that the practice is inappropriate. Formal incest taboos are the cultural reinforcement of the automatic inhibition, an example of the way culture is shaped by biology. But these various surface manifestations need not be consulted in order to formulate a more robust technique of moral reasoning. What matters in this case is the juvenile inhibition: the measures of its strength and universality, and a deeper understanding of why it came into being during the genetic evolution of the brain. (Ruse, 184)
This example is taken to be an example of “the existence of epigenetic rules- constraints rooted in our evolutionary biology that affect the way we think” (Ruse, 185). These rules are “directly related to adaptive advantage” and “extend into the moral sphere” (Ruse, 185).
One response that Ruse anticipates is the claim that he’s merely given one example of how biology can place constraints on our moral convictions, and the incest example seems plausible enough. However, this obviously doesn’t exhaust the entirety of the human moral dimension. Ruse replies by admitting this and yet points out that epigenetics is still in its infancy and more work needs to be done, and through the cooperation of psychologists, biologists, and philosophers all working together we can find similar epigenetic rules underlying much of our moral theorizing.
After laying down his empirical case, Ruse moves on to the alleged meta-ethical implications of biology. The implications of biology for morality are that
there can be no genuinely objective external ethical premises. Everything that we know about the evolutionary process indicates that no such extrasomatic guides exist (Ruse, 186).
And why is this? The reasoning Ruse gives seems confused and unclear, and thus worth quoting generously at length before we pick it apart. He writes that
It follows from what we understand in the most general way about organic evolution that ethical premises are likely to differ from one intelligent species to another. The reason is that choices are made on the basis of emotion and reason directed to these ends, and the ethical premises composed of emotion and reason arise from the epigenetic rules of mental development. These rules are in turn the idiosyncratic products of the genetic history of the species and as such were shaped by particular regimes of natural selection. For many generations- more than enough for evolutionary change to occur- they favoured the survival of individuals who practiced them. Feelings of happiness, which stem from positive reinforcers of the brain and other elements that composed the epigenetic rules, are the enabling devices that led to such right action (Ruse, 186).
It is difficult to know what Ruse means by “ethical premises” in the above passages. It seems that according to Ruse an “ethical premise” is simply an ethical judgment or belief according to which we are predisposed to act. Ethical premises are simply the moral judgments that we actually hold. These ethical judgments are, on Ruse’s view, the products of the genetic history of the species and as such are contingent insofar as they were shaped by local factors peculiar to the particular species in question. If “ethical premises” are the result of such forces then it is unlikely that evolution would be likely to “program” universally shared ethical premises across all species. This is because these “ethical premises” would then be individual to the genetic history of each species, and its particular fitness (Ruse, 186). Consequently “No abstract moral principles exist outside the particular nature of individual species” (ibid).
The problem with this argument is simply that the conclusion does not follow. If “moral premises” are simply the moral beliefs of a species, and I believe this is what the text indicates, then it simply does not follow that because our moral beliefs have been shaped (or determined to a certain extent) by the forces of evolution there is therefore no fact of the matter about how we ought to act. If evolution has programmed us to believe we should “do unto others as we would have them do unto us”, it is a separate and further question whether that is indeed how we ought to act. The fact that evolution has shaped what we think proper norms of behavior are does not have any bearing on whether there are belief-independent norms of behavior in the first place.
One could easily grant Ruse the claim that different intelligent species could evolve in isolation from one another and come to develop different standards of behavior. Their moral beliefs would differ, but of course what the moral realist claims is that there are mind-independent norms of conduct that do not depend on the beliefs of the individuals who hold them for their existence or truth. Ruse seems to think that because evolution would “program” different species to accept different moral codes this gives us reason to doubt the existence of mind-independent and species transcendent moral truths. But why should we believe this? Ruse says that
It is easy to conceive of an alien intelligent species evolving rules its members consider highly moral but which are repugnant to human beings, such as cannibalism, incest, the love of darkness and decay, parricide, and the mutual eating of faeces. Many animal species perform some or all of these things, with gusto and in order to survive. If human beings had evolved from a stock other than savanna-dwelling, bipedal, carnivorous man-apes we might do the same, feeling inwardly certain that such behaviours are natural and correct (Ruse, 186).
Even if this conditional is true, how is that relevant to the truth of whether we ought to value such things? Ruse concludes by saying that
It follows that the ethical code of one species cannot be translated into that of another. No abstract moral principles exist outside the particular nature of individual species (Ruse, 186).
Once again we have a non-sequitur. It no more follows that there are no abstract moral principles because two individuals have a moral disagreement than it does whenever two species disagree (if it were ever to happen). Moral disagreement can be evidence for the non-existence of mind-independent moral principles only if we would expect greater convergence in the moral beliefs of members in a species or between species if such principles existed, but Ruse doesn’t argue for this latter point so much as simply assumes it. There is a wealth of literature on realist accounts of moral disagreement that are compatible with moral realism, none of which Ruse bothers to engage with.
As a philosopher of biology, Ruse is perfectly aware of the amount of disagreement within the U.S. population about the status of evolutionary theory as the best explanation for the origins of human beings and other lifeforms in the planet. As Sarah McGrath points out in Moral Disagreement and Moral Expertise (2007):
According to a Harris Poll conducted in the summer of 2005, only one-fifth of Americans believe that human beings evolved from other species; only half think that other plants or animals did; 64 percent believe that “human beings were created directly by God”. (McGrath, 89).
But of course we do not (and should not) draw the conclusion that there are no facts about human origins because of the widespread disagreement found in the population. Even if there were widespread disagreement among experts in biology we should not draw the conclusion that there are no facts about human origins. We might be weary and conclude that we have no reason to believe that our beliefs accurately track the facts in question, but that would be an epistemic challenge to overcome, and Ruse wants to draw a metaphysical conclusion from the alleged fact that different species would develop different moral beliefs (a case of moral disagreement) to the negative existential claim that consequently there are no moral facts. Widespread disagreement may lead to the conclusion that we have a defeater for our moral beliefs thus rendering them unjustified, but disagreement does not entail that there are no relevant facts of the domain in question.
Further, Ruse writes:
It is thus entirely correct to say that ethical laws can be changed, at the deepest level, by genetic evolution. This is obviously quite inconsistent with the notion of morality as a set of objective, eternal verities (Ruse, 186).
Here Ruse is quite clearly equivocating in his use of “ethical laws”. In the first sense he’s using “ethical laws” to simply mean the moral convictions and beliefs of a species that have been shaped by the genetic evolution of that species and using the fact that these convictions can and have changed draws the conclusion that objective “ethical laws” (in the second, mind-independent sense) don’t exist. Since mind-independent ethical laws are supposed to be eternal and unchanging, an observation that they change entails their non-existence. But of course his observation entails no such thing. The moral laws haven’t changed, moral beliefs have, and the two are not the same. That moral beliefs have changed throughout history and have differed between cultures does not mean that moral laws have changed, rather, it simply means that what we thought were the moral laws has changed. The fact that biological factors have and continue to play a role in the development of our moral beliefs does not entail that there aren’t mind-independent moral facts to which these beliefs correspond any more than sociological pressures entail such a thing. The average individual’s acceptance of slavery during the 19th century was no doubt influenced by the surrounding cultural acceptance of the practice, but the fact that sociological factors played such a role in people’s approval of the institution of slavery did not and does not entail that there is no fact of the matter as to slavery’s unjust nature. Biological considerations aren’t what are carrying the weight in Ruse’s argument but rather an appeal to the origins of the beliefs in question that are leading him to infer that the beliefs are without referents. In making this jump Ruse seems dangerously close of committing the genetic fallacy.
The Epistemic Challenge
While I believe Ruse’s metaphysical jump to a negative existential about moral facts is too quick an unjustified, I believe there is an epistemic hurdle that evolutionary considerations raise that must be overcome. The hurdle is quite simply this:
What reason is there to presume that our present state of evolution puts us in correspondence with ultimate truths? (Ruse, 187)
Earlier Ruse argued from evolutionary considerations to the conclusion that there aren’t any moral truths, though that leap was unjustified. We can, however, shift the argument from a metaphysical to an epistemological argument. Instead of concluding that evolutionary considerations force upon us the conclusion that there are no moral facts we may come to find that evolutionary considerations force us to conclude that even if there are moral truths, there is no reason to suppose that we possess knowledge of such truths and that there is no reason to suppose that evolutionary forces would steer us in the right direction towards those truths. Instead of concluding that our moral beliefs are false and illusory, this line of argumentation merely seeks to call into question the justification of our moral beliefs. Several authors have recently posed this challenge more forcefully than Ruse, though for the sake of space I will stick with Ruse’s challenge.
If something roughly like Ruse’s evolutionary genealogy of our moral beliefs is true, do we have any reason to suppose that our moral beliefs are likely to correspond to the moral facts that moral realists posit? I will draw from Knut Olav Skarsaune’s work to argue that there is indeed one plausible way in which evolution could equip us with moral beliefs that are truth conducive. Skarsaune’s argument in Darwin and Moral Realism: Survival of the Iffiest (2011) takes the form of a conditional:
If pleasure is usually good and pain usually bad, there does indeed exist a relation between evolutionary pressures and the evaluative facts, a relation which is truth-conducive in the sense that it would tend to bias our evaluative beliefs toward the truth (Skarsaune, 233).
Skarsaune’s strategy is to point out that “evolution has caused us to value reproductively beneficial things by making us such that we take pleasure in these things, and caused us to disvalue reproductively harmful things by making us such that these things cause us pain” (Skarsaune, 233). From this Skarsaune reasons that if the proposition P: pleasure is usually good and pain is usually bad is true then
to the extent that evolution has influenced our evaluative beliefs through the mechanism just described, that influence has been truth-conducive. For if pleasure is usually good, then the activities and states of affairs evolution has caused us to value through this mechanism tend to be good- because they are pleasurable. Hence, if P is true, there is a relation between reproductive enhancement and goodness after all (Skarsaune, 2011, p. 234).
This is what Skarsaune calls the “pre-established harmony account”: “if pleasure is (usually good), then it was pre-ordained ahead of time, as it were, that (almost) whatever evolution should happen to make us value through this mechanism, it would thereby also imbue with value” (Skarsaune, 235). Evolution has not made pleasurableness good; that would be an independent evaluative fact. The role evolution has played is “simply making these states of affairs pleasurable. But once evolution has done that, the independent evaluative fact ‘kicks in’, as it were, the end result being that these states of affairs are good” (Skarsaune, 235).
n fact, Skarsaune is doubtful that evolutionary mechanisms are responsible for much beyond our pleasure/pain considerations. While Ruse gave the example of incest and a promisory IOU voicing optimism about the prospects of sociobiology to explain most if not all of our moral theorizing in terms of epigenetic rules, Skarsaune is skeptical about the strength of Darwinian influences beyond the mechanism involving pleasures and pains upon our evaluative beliefs. He writes that
While we can’t help but think that it is bad to starve, to have our arms and legs broken, or to be shunned by everyone we know, it seems we can’t help but embrace the beliefs corresponding to other kinds of innate evaluative tendencies (Skarsaune, 235).
The anti-realist should therefore
move beyond the general claim that evolution has had a profound impact upon our evaluative beliefs. For the pleasure-pain mechanism may well be the main thing that makes this general claim true, and as I have argued, if we assume the truth of P, then that mechanism is truth-conducive (Skarsaune, 236).
The evolutionary anti-realist is therefore burdened with giving an account of just how widespread the “poisoning” of illegitimate Darwinian influences on our moral theorizing has been beyond our evaluative tendencies towards pleasure and pain.
The upshot of Skarsaune’s account is that if P is false, that is if the claim that “pleasure is usually good and pain usually bad” is false, then human morality is in big trouble anyway. Given how widespread pain and pleasure considerations are in our ethical theorizing, if it turned out that we are seriously mistaken about pleasure and pain then we would be seriously mistaken about most of ethics in general. So, is P is true then we have good reason to believe that evolutionary forces have steered us in the right direction, at least generally. If P is false then we’re in big trouble anyway, regardless of any Darwinian considerations.
To summarize, I have argued that Michael Ruse’s argument that evolutionary considerations reveal the illusory nature of morality fails. His argument collapses into an argument from moral disagreement, but moral disagreement does not entail the non-existence of moral facts. Moral disagreement may call into question the justification of our moral judgments, but as we have seen, there are plausible accounts on offer that can make us feel more at ease in a Darwinian world. Though it remains to be shown precisely that all attempts to dethrone meta-ethical objectivity via the lens of evolutionary biology fall with Ruse, it is at least compelling that such a concerted and quintessential case as Ruse’s fails without touching what it hoped to destroy.
McGrath, Sarah (2007). Moral disagreement and moral expertise. In Russ Shafer-Landau (ed.), Oxford Studies in Metaethics Vol. 4. Oxford University Press.
Michael Ruse & Edward O. Wilson (1986). Moral Philosophy as Applied Science. Philosophy 61(236):173-.
Skarsaune, Knut Olav (2011). Darwin and moral realism: Survival of the iffiest. Philosophical Studies 152 (2):229–243.