What are the most fundamental discoveries we have made about the universe? I don’t mean what are the most fundamental things we know about the universe; I mean to ask about what we have discovered (revealed, unearthed, found out unexpectedly). I think there are three: atoms, universals, and forces. We have discovered that ordinary objects are made of invisible particles agglomerated together; we have discovered that there are universals as well as particulars; and we have discovered that the universe contains forces as well as the vehicles of forces. We can credit the first two discoveries to the ancient Greeks (specifically Democritus and Plato) and the third to Newton (though his discovery had antecedents). These basic discoveries have been deepened and elaborated, and much of science and philosophy is built around them: types of atoms, types of universals, and types of forces. But the fundamental discovery in each case consists in a single general idea—the idea of invisible particles composing visible objects, the idea of general properties in addition to the particulars that instantiate them, and the idea of a small number of forces that govern how things behave. None of these things is evident to the senses or known innately or easily verified: they are speculative, bold, and open to controversy. To make these discoveries the human mind had to transcend common sense; evidently no other animal has succeeded in duplicating this feat. We might say that they represent scientific knowledge, construed as including the discovery of universals. They have in common the property of attributing an extra layer of reality to things—a kind of additional world. We have the world of atoms, the world of universals, and the world of forces: there is thus more to the universe than visible objects, particulars, and bodies in motion. In so far as these extra realities are hidden, we have discovered that much of reality is a hidden reality. The big general discovery is that the universe is more than appears to us: this is a discovery about our limited powers of perception, or equivalently the indifference of reality to our contingent minds.
As a consequence the three discoveries have been resisted and reformulated: maybe atoms are just abstractions form ordinary perceptions of objects; maybe so-called universals are logical constructions from particulars; maybe talk of forces is just disguised talk of the behavior of objects. We have thus discovered that such discoveries are controversial, but the discoveries themselves cannot be gainsaid. We need to incorporate these insights into any comprehensive picture of reality. And together they point to an important truth about nature: nature is rife with generality. The atoms are of only a few basic types (especially when we venture into their internal structure); there are many fewer universals than particulars and they are repeated everywhere; and the forces are limited to just four, gravity and electromagnetism being the basic two so far as ordinary observation is concerned. The multitude of particular things we observe is accompanied by relatively few discovered general things; so we have discovered that the world is more parsimonious than we might have supposed. The laws governing atoms are indicative of a basic uniformity: a few types of atoms, a few properties of these atoms, and a handful of forces acting on them. We have discovered that nature is fundamentally simple, almost miserly, not the rich variegated pageant we naively supposed. This is a startling discovery that took a long time to mature and crystalize. Nature is all about uniformity and repetition.
Once we have these discoveries firmly in mind we can ask a vertiginous question about them: are they true of all of nature? They are true of the parts of nature we have examined, but might they be false of other parts? Do they have only a local validity? We can ask this regarding parts of actual space and time, but we can also ask it more broadly of other universes that might exist alongside ours, and also of merely possible universes. Is matter everywhere made of atoms? Do we always find a sharp distinction between particulars and universals? Is there always a force-vehicle distinction? What about the universe before the big bang when atoms had not formed and the four forces of our current universe had not yet emerged? Are there conceivable forms of matter that don’t divide neatly into the particular and the general? Might the mind be an area of reality in which these distinctions don’t really hold up? Are there mental atoms? Does the mind admit of a clear particular-universal distinction? Are thoughts and emotions subject to gravity and electromagnetism? It appears conceivable that our prized trinity of discoveries has only a relatively local application, being derived from an analysis of what confronts our senses on a daily basis. They could have turned out not to be true of our local world, and they might not be true of every actual or conceivable world. Our most fundamental discoveries might be parochial or even atypical compared to reality as a whole. Maybe what we have investigated hitherto is an unrepresentative sample.