Darwin proposed, back in 1859, that species arose due to natural selection—the pruning of deleterious genetic variations in a population, which led to the thinking that the “inherent design” in nature, formerly thought to be due to a designer (“God”) was due to a force Darwin called “natural selection” (NS). The line of reasoning is thus: (1) two individuals of the same population are mostly the same genetically/phenotypically, but have small differences between them, and one of the small differences is a difference in a trait needed for survival. (2) But both traits can contribute to fitness, how does NS ‘know’ to select for either coextensive trait? Now think about two traits: trait T and trait T’. What would explain the fixation of either trait in the population we are discussing? NS is not—cannot—be the mechanism of evolution.
In 2010, philosopher Jerry Fodor and cognitive scientist Massimo Piattelli-Palmarini, wrote a book titled “What Darwin Got Wrong“, which argued that NS is not a causal mechanism in regard to the formation of new species. Their argument is (pg 114):
- Selection-for is a causal process.
- Actual causal relations aren’t sensitive to counterfactual states of affairs: if it wasn’t the case that A, then the fact that it’s being A would have caused its being B doesn’t explain its being the case that B.
- But the distinction between traits that are selected-for and their free-riders turns on the truth (or falsity) of relevant counterfactuals.
- So if T and T’ are coextensive, selection cannot distinguish the case in which T free-rides on T’ from the case that T’ free-rides on T.
- So the claim that selection is the mechanism of evolution cannot be true.
This argument is incredibly strong. If it is true, then NS cannot be the mechanism by which evolution occurs; NS is not—nor can it be—the mechanism of evolution. So, regarding the case of two traits that are coextensive with each other, it’s not possible to ascertain which trait was selected-for and which trait was the free-rider. NS cannot distinguish between two locally coextensive traits, so, therefore, it is not an explanatory mechanism and does not explain the evolution of species, contra Darwin. It cannot be the mechanism that connects phenotypic variation with fitness variation.
The general adaptationist argument is: “(1) the claim that evolution is a process in which creatures with adaptive traits are selected and (2) the claim that evolution is a process in which creatures are selected for their adaptive traits” (Fodor and Piattelli-Palmarini, 2010: 13). Darwinists are committed to inferring (2) from (1), though it is fallacious. It is known as the intensional fallacy.
“Due to the intensionality of “select-for” and “trait”, one cannot infer from ‘Xs have trait t and Xs were selected’ to ‘Xs were selected for having trait t’” (Fodor and Piattelli-Palmarini, 2010: 139). How does one distinguish from a trait that was selected-for and a free-rider that hitched a ride on the truly adaptive trait for the organism in question? The argument provided above shows that it is not possible. “Darwinists have a crux about free-riding because they haven’t noticed the intensionality of selection-for and the like; and when it is brought to their attention, they haven’t the slightest idea what to do about it” (Fodor and Piattelli-Palmarini, 2010: 16).
No observation can show whether or not trait T or T’ was selected-for in virtue of its contribution to fitness in a given population; favoring one story over another in regard to the adaptation of a trait in question, therefore, does not make any logical sense due to the problem of free-riders (and, also, favoring one story over another is due to bias for the like of the specific adaptive just-so story in question). For if two traits are coextensive—meaning that traits coincide with one another—then how can NS—which does not have a mind—‘know’ to “select-for” whichever trait contributes to fitness in the population in question? Breeders are the perfect example.
Breeders have minds and can therefore select for certain traits and against undesirable traits; however, of course, since NS does not have a mind, this is not the case when it comes to naturally selected traits (so-called), since NS does not have a mind. NS cannot explain the distribution of phenotypic traits throughout the world; there is no agent of NS nor are there ‘laws of selection’, therefore NS is not an explanatory mechanism. Explanations based on NS are based only on correlations with traits and fitness, not on causes themselves (this critique can be extended to numerous other fields, too). The problem with relying only on correlations between traits and fitness is two-fold: (1) the trait in question can be irrelevant to fitness and (2) the trait in question can be a free-rider.
Creatures have traits that increase fitness because they were selected-for, the story goes. NS explains why the creature in question has trait T, which increases fitness in environment E. One can then also make the claim that the selection of the trait in question was due to the increased fitness it gave the creature. However, if this claim is made, “then the theory of natural selection would reduce to a trait’s being a cause of reproductive success [which then] explains its being a cause of reproductive success which explains nothing (and isn’t true).”
So since genetically-linked traits are coextensive with an infinitude of different possible outcomes, then the hypothesis that trait X is an adaptation is underdetermined by all possible observations, which means that NS cannot explain how and why organisms have the traits they do, since NS cannot distinguish between two coextensive traits, since NS lacks a mind and agency.
NS can be said to be an explanation if and only if two conditions are met: (1) if NS can be understood as acting on counterfactuals and (2) if NS can be said to be acting on any physical evolutionary laws.
(1) A counterfactual is an “if-clause”, which is contrary to a fact. A counterfactual is a statement that cannot be true, for example, “I hear but I have no ears” or “I see but I have no eyes.” Thus, if it were possible for NS to be an explanation for the continuance of a specific trait that is linked to other traits (that is, they are coextensive) in a given population, it would need to—necessarily—invoke a counterfactual about NS. It would need to be the case that the trait in question would still be selected for in the absence of free-riders. As an example from Fodor and Piattelli-Palmarini (2010: 103) a heart pumps blood (what it was selected-for) and makes pumping sounds (its linked free-rider). Thus, if the pumping of blood and the sound that blood-pumping makes were not coextensive, then the pumping, not the pumping sounds, get selected for.
There is a huge problem, though. Counterfactuals are intentional statements; they refer to concepts found in our minds, not any physical things. NS does not have a mind and thus lacks the ability to “select-for” since “selecting-for” is intentional. Therefore NS does not act on counterfactuals; it is blind to the fact of counterfactuals since it does not have a mind.
(2) It does not seem likely that there are “laws of selection”. Clearly, the adaptive value of any phenotype depends on the environment that the organism is in. Fodor and Piattelli-Palmarini (2010: 149) write (emphasis theirs):
The problem is that it’s unlikely that there are laws of selection. Suppose that P1 and P2 are coextensive but that, whereas the former is a property that affects fitness, the latter is merely a correlate of a property that does. The suggestion is that all this comes out right if the relation between P1 and fitness is lawful, and the relation between P2 and fitness is not. …it’s just not plausible that there are laws that relate phenotypic traits per se to fitness. What (if any) effect a trait has on fitness depends on what kind of phenotype is embedded in, and what ecology the creature that has the trait inhabits. This is to say that, if you wish to explain the effects that a phenotypic trait has on a creature’s fitness, what you need is not its history of selection but its natural history. And natural history offers not laws of selection but narrative accounts of causal chains that lead to the fixation of phenotypic traits. Although laws support counterfactuals, natural histories do not; and, as we’ve repeatedly remarked, it’s counterfactual support on which distinguishing the arches from the spandrels depends.
There is, too, a simple example regarding coextensive traits and selection. Think of the lactase gene. It is well-known that we humans are adapted to drink milk—and the cause is gene-culture coevolution that occurred at around the time of cow domestication (Beja-Perreira et al, 2003; Gerbalt et al, 2011). No one disputes the fact that gene-culture coevolution is how and why we can drink milk. But what people do dispute is the adaptive just-so story (Gould and Lewontin, 1976; Lloyd, 1999; Richardson, 2007) that was made to explain how and why the trait went to fixation in certain human populations. Nielsen (2009) writes (emphasis mine):
The difference in lactose intolerance among human geographic groups, is caused by a difference in allele frequencies in and around the lactase gene (Harvey et al. 1998; Hollox et al. 2001; Enattah et al. 2002; Poulter et al. 2003). The cause for the difference in allele frequencies is primarily natural selection emerging about the same time as dairy farming evolved culturally (Bersaglieri et al. 2004). Together, these observations lead to a compelling adaptive story of natural selection favoring alleles causing lactose tolerance. But even in this case we have not directly shown that the cause for the selection is differential survival due to an ability/inability to digest lactose. We must acknowledge that there could have been other factors, unknown to us, causing the selection acting on the region around the Lactase gene. Even if we can argue that selection acted on a specific mutation, and functionally that this mutation has a certain effect on the ability to digest lactose, we cannot, strictly speaking, exclude the possibility that selection acted on some other pleiotropic effect of the mutation. This argument is not erected to dispute the adaptive story regarding the lactase gene, the total evidence in favor of adaptation and selection related to lactose tolerance is overwhelming in this case, but rather to argue that the combination of a functional effect and selection does not demonstrate that selection acted on the specific trait in question.
Selection could have acted on a free-rider that is coextensive with the lactase gene, and just because “the story fits the data” well (that’s a necessary truth; of course the story can fit the data because any story can be formulated for any data) does not mean that it is true, that the reason for trait T is reason R since they “fit the data so well.”
Of course, this holds for EP, evolutionary anthropology, and my favorite theory for the evolution of human skin color, the vitamin D hypothesis. I do not, of course, deny that light skin is needed in order to synthesize vitamin D in climates with low UVB; that is a truism. What is denied is the fact that selection acted on light skin (and its associated/causal genes); what is denied is the combination of functional effect and selection. Just-so stories are necessarily true; they, of course, fit any data because one can formulate any story to fit any data points they have. Thus, Darwinists are just storytellers who have a bunch of data; there is no way to distinguish between the selection of a trait because it increased fitness and the selection of a free-rider that is “just there” that does not increase fitness, but the thing that increases fitness is what the free-rider “rode in on.”
NS is not and cannot be an explanatory mechanism. Darwinism has already been falsified (Jablonka and Lamb, 2005; Noble, 2011; Noble, 2012; Noble, 2017) and so, this is yet another nail-in-the-coffin for Darwinism. The fact that traits that are coextensive means that NS would have to “know” which trait to act on; NS cannot “know” which of the coextensive traits to act on (because it has no mind) and, NS cannot be a general mechanism that connects phenotypic variation to variation in fitness. NS does not explain the evolution of species, nor can NS distinguish between two locally coextensive traits—traits T and T’—because NS has no agency and does not have a mind. Therefore NS is not an explanatory mechanism. Just invoking NS to explain the continuance of any trait fails to explain the survival of the trait because NS cannot distinguish between traits that enhance an organism’s fitness and free-riders which are irrelevant to survival but are coextensive with the selected-for trait, as long as the traits in question are coextensive.
P1) If there is selection for T but not T’, various counterfactuals must be true.
P2) If the counterfactuals are true, then NS must be an intentional-agent, or there must be laws about “selection-for”.
P3) NS is mindless.
P4) There are no laws for “selection-for”.
∴ It is false that selection for T but not T’ occurs in a population.
One then has two choices:
(1) Argue that NS has a mind and therefore that it can “select for” certain traits that are adaptable in a given population of organisms in the environment in question. “Select-for” implies intention. Intentional acts only occur in organisms with minds. Intentional states are only possible if something has a mind. Humans are the only organisms with minds. Humans are the only organisms that can act intentionally. NS does not have a mind. (Animal breeder’s are an example that can select-for desirable traits and against undesirable traits because animals breeder’s are humans and humans can act intentionally.) Therefore NS does not act intentionally since it does not have a mind. I don’t think anyone would argue that NS has a mind and acts intentionally as an agent, therefore P3 is true.
(2) Argue that there are laws for “selection-for” phenotypic traits related to fitness. But it’s not possible that there are laws that relate to the selection of a phenotype, per se, in a given population. The effect of a trait depends on the ecology of the organism in question as well as its natural history. Therefore, to understand the effects of a phenotypic trait on the fitness of an organism we must understand its natural history, not its selection history (so-called). Therefore P4 is true.
There are no laws for “selection-for”, nor does NS have a mind that can select a trait that lends to an organism’s fitness and not a trait that’s just correlated with the trait in question