I want to consider, in light of fairly new philosophical and scientific research, two long-standing conceptual objections to evolutionary theory: Wallace’s Problem and Darwin’s Doubt.
It is well-recognized that Wallace saw the need for some supernatural intelligence in explaining human evolution, in contrast to Darwin’s naturalistic speculations in Descent of Man. What is less recognized is that Wallace was, in an important sense, right. He squarely faced the problem, “can natural selection alone account for the unique cognitive abilities of human beings, such as abstract thought, self-consciousness, radical reshaping of the environment (e.g. clothing, building), collective self-governance by ethical norms, and the symbolic activities of art, religion, philosophy, mathematics, logic, and science?” Whereas Darwin thought there was continuity between humans and non-human animals, his evidence is primarily amount emotional displays, rather than the genuinely cognitive discontinuity.
A closely related problem, however, was squarely faced by Darwin: the question, nicely phrased in his famous letter to Asa Gray, as to whether it is plausible to think that natural selection can have equipped a creature with a capacity for arriving at any objective truths about the world. (It is not often noted that in that letter, Darwin says that he believes in an intelligent creator — what is in doubt is whether natural selection gives him reasons to trust in his cognitive abilities.)
These two questions, Wallace’s Problem and Darwin’s Doubt, are two sides of the same coin: if natural selection (along with other biological processes) cannot account for the uniquely human ability to grasp objective truths about reality, then we must either reject naturalism (as Wallace did) or question our ability to grasp objective truths about reality (as Darwin did).
Call this the Cognitive Dilemma for Naturalism. Can it be solved? If so, how?
What I want to suggest is that we can solve Wallace’s Problem and resolve Darwin’s Doubt by assembling the following materials.
1. A philosophical revolution that I call “embodied discursive pragmatism”. Discursive pragmatism, in C. I. Lewis, W. Sellars, and Robert Brandom treats language as logically prior to thought, such that we can explain intentionality and semantic content in terms of language (rather than treating language as the mere vehicle by which logically independent thoughts are communicated). Language here is a kind of activity; languaging is something that we do, and we are enlanguaged beings because of what we have learned to do. To this, embodied discursive pragmatism stresses that language is itself a particular way of being an embodied being — speech (and writing) are themselves ways of enacting an embodied way of life.
2. Recent work in niche construction theory, embodied-embedded cognitive science, comparative primatology, and paleoanthropology (none of which were available to Wallace or Darwin).
Assembling these philosophical and scientific resources allows us to understand how, in the first instance, many animals generally are able to arrive at a primitive kind of proto-objective (and proto-subjective) knowledge by being able to reliably track objects across space and time (even when not being perceived directly), recognize that co-occurent sensing through different sensory modalities can have the same spatio-temporally coextensive causes, correlate exteroceptive and interoceptive information (necessary for distinguishing movement-caused perceptual changes and perceptual changes not caused by the animal’s own movement), learn, predict, imagine, and infer.
In the second instance, the construction of a uniquely hominid niche involved obligate cooperative extractive foraging. While extractive foraging is common in primates, and many great apes use tools to extract foods from their environments, humans are cooperative in extractive foraging (and must be so). Adequate provisioning requires that everyone in the group who is able to contribute will in fact contribute to the provisioning of everyone else, through division of labor that involves hunting and scavenging; setting traps for small animals; gathering nuts, seeds, berries and herbs for foods and medicines; cleaning and cooking food, making clothing, weapons; transmitting to future generations the knowledge of how to do all these things through active teaching.
Obligate cooperative foraging involves two important cognitive transformations: displaced reference and joint intentionality. Displaced reference, which put hominids on the road to language, is the capacity to communicate about objects and events that are not perceptually present to (at least) the hearer. Joint intentionality is the ability for two creatures to take an object as their shared object of attention, to know of the other creature that it is also attending to that object and to want them to do so, so that the two creatures can coordinate their actions in order to succeed at a task that neither of them could accomplish alone (or which would take much more time or energy to do so).
Displaced reference as a communication system, whether vocal or gestural, puts hominids on the road to language. (The next major hurdle would the evolution of syntax.) Joint intentionality puts hominids on the road to collective intentionality and thence to culture, art, religion, exchange of goods and services, and so on.
But once we see, with embodied discursive pragmatism, that all there is to be explained is our ability to play the socio-linguistic game of giving and asking for reasons as itself a particular form of animal embodiment, then we can see that there are no insurmountable obstacles to getting to that point from a sufficiently rich, empirically informed of animal cognition in general and of primate cognition in particular.
And thus we can solve Wallace’s Problem and resolve Darwin’s Doubt: we can explain our capacity for rational discourse and objective thought in naturalistic terms.