A Linguistic Universal
We are familiar with claims of linguistic universality: the noun-verb form, recursive embedding, quantificational structure, adverbial modification, discrete infinity, and the like. I want to add a different kind of linguistic universal, one that is less syntactic than semantic: I call it “material plurality”. A natural language like English contains resources for covering three large domains: the world of material objects in space, the psychological realm, and ethical concerns. It also contains specialized technical vocabulary such as we find in theoretical physics and linguistic analysis, but these are not the core components of the language. It is evident that other natural languages contain the same basic range of resources. This is not surprising given that we acquire the whole threefold package more or less simultaneously.  There is good reason to believe that all three domains correspond to innate cognitive resources, possibly organized into distinct modules. But there is no logical necessity about this: it could have been otherwise. It is logically conceivable that a child should acquire one or two of these types of linguistic competence but not all three. Animal communication systems don’t encompass such a wide range of subject matters, but human languages always incorporate reference to the three domains in question. They are logically dissociable but not actually ever dissociated. There is a certain kind of holism at work, biologically based. Thus human languages exhibit the universal of material plurality with respect to these three areas. This is not a syntactic universal but a semantic one; it concerns what human languages are about. It is non-trivial and counts as an empirical regularity. We have an innately based universal of linguistic clustering. We could have had merely local clustering, or no systematic clustering at all, but in fact we find that all human languages obey a principle of material plurality—a de facto conjunction of differing linguistic systems. The human language faculty incorporates resources suitable for physics, psychology, and ethics (of the common sense varieties)
Presumably the linguistic is underlain by the cognitive: we also have an innately based cognitive clustering. Again, there is nothing a priori about this: it could have been otherwise. But in fact the human mind comes prepackaged with three separable components corresponding to the external world, the internal world, and the normative world. There are no (normal) people that function using only one or two of these three modules: everyone is a commonsense physicist, an amateur psychologist, and an opinionated ethicist. This is the way the human brain is contingently organized. For us, the world comes arranged into the physical, the mental, and the ethical—with connections between them. We are cognitively tripartite. Each area has its own ontology, organizing principles, and theoretical assumptions; but we effortlessly master all three together. We are not like schoolchildren learning history before geography or algebra after music. The pre-school developing mind doesn’t first understand the external world, then graduate to the psychological world, and finally ascend to the dizzy heights of ethics: all of it emerges as a whole, despite the variety of subject matter. That is a remarkable fact, and a remarkable achievement: it is an awful lot to take in (or allow to grow internally). But we all do it, quickly, smoothly, and without concentrated study. We might encounter aliens with a grasp of only part of this grand cognitive structure (they are shaky when it comes to ethical thinking—see the Klingons). But we humans universally grasp all three domains and use them as a basis for more specialized study.
Why do we exhibit this particular pattern of linguistic and cognitive mastery? Why did we evolve so as to install these three types of competence? The answer is not far to seek: we are a social species with sophisticated social cognition (quite a bit above bees and ants). We clearly need to grasp the workings of the material environment, but we also need to understand and predict our fellow humans, because their behavior affects our own welfare—we need a folk psychology. But with that comes the need to police behavior—to censure and criticize, punish and deter. We need ethics in some form. Quite possibly ants and bees have some sort of counterpart to this given their intensely social life, but we humans need it in spades because of our complex social relations. Not to possess one of these competences would severely disadvantage a human being, rendering him or her incapable of productive human interaction. So we would expect a robust innate program for developing the mature competences that we see universally exhibited. Thus we are not just Homo sapiens but also Homophysicists-psychologists-ethicists. It is our human nature to instantiate these three sorts of competence. Possibly other primates have the rudiments of all three competences, but in us they reach a high level of sophistication. 
 I say this not because I know of detailed scientific studies that establish it but because of common observation (a neglected source of data). It would be interesting if minute differences of cognitive scheduling could be detected between the three areas.
 This doesn’t mean they are incapable of improvement: we are not omniscient physicists, psychologists, and ethicists. We might be sharply limited in all three areas. But our cognitive patrimony includes a substantial helping of each of them.