Why did modern science succeed so well? Perhaps because it really did give up on the action of a substance as the fundamental causal power. (Plato and Aristotle, for instance, seem to suppose that real causal action must involve a substance as agent cause, even if it is a substance considered as it bears a certain essential quality, such as heat in fire.) Instead it turned to analysis of the actions of qualities, and mere masses (mechanics). So heat becomes a sort of substance, if you will, but we still call it heat! Once you can measure a quality, and say how much, it begins to look like some sort of stuff. If one makes a physical object a substance, it is a mass, say, which exerts gravitational influence, and it is the mass, a quality of it, that seems active, or we might say the substance is active only in virtue of this quality. If we try to get at the real substance underlying all the qualities, we end up with something that scarcely seems to be included in the causal account at all, except perhaps as a locus of qualities. And so physical objects might be replaced in our thinking with space, together with certain properties identifiable in terms of fields.
Atomism looked at the masses and asked how they acted upon one another, and the notions of mechanics could be established in part in Greek thought, though the reasons why an atom is impenetrable and maintains its shape was left unexplained. Nowadays we might explain such things (the electric fields around the outer layer of atoms that repel the electrons of the outer layer of atoms in any mass approaching it, and the crystalline structure, say). But qualities could only be examined once mathematics could be applied to them, so the notion of degrees of heat and the like, which seems to have been contrived in the 14th and 15th centuries, was perhaps an essential step on the way to modern science. I guess first theories were formed concerning heat and temperature, which led to a supplementation of mechanics with a more general conception of energy, and then the breakthrough in chemistry (connected to conservation of energy, measurements how much energy is in . . .? ), the development of the notion of a particle defined in terms of its propensity to attract and repel other particles due the presence of some quality in it (at first Newtonian hypothetical point masses to simplify calculations for extended masses, then electrons as “real” point masses, and point electric charges as well) and fundamental was also the application of measurement to wave phenomena through frequency, period and amplitude, and the analyses first of circular orbital motions, and then, using that math, applying it to the wave theory of light, eventually joined to the other work by Maxwell’s notion that light consists in electromagnetic waves. So an analytic vocabulary was developed making possible the reconstruction of phenomena in terms of physical objects located in space. In all this the actions of substances were either ignored, or treated as measurable and mechanical. Finally the mechanical substance becomes a singularity in a field, with location and continuous motion, and its causal properties no longer involve collisions and rebounds at all, but rather the formation of fields which influence the movements of other particles and produce such “collisions”. It is explained why the intuitive notion of the solid object finds application in the world, but solid objects are constructed out of other sorts of things, or perhaps eliminated from our ontology? After they had been ignored long enough, the project of reconstructing substances of chemical sorts (stuff, matter) and biological sorts, that is, reduction of biology to chemistry and physics, chemistry to subatomic physics, and so on, proceeded apace. It must be admitted that this reduction strategy, however suspicious it may look, and the construction of models, was indispensable to the whole development. (Note also that subjective vs. objective phenomena played no role, or rather, the subjective and intentional was simply ignored, and perhaps now is being addressed with physical reconstruction in a functionalist way.) This is not to say that the initial attention to the analogy of things to ourselves was ignored, since our physical selves are as much the objects of immediate knowledge to us as our mental selves (perhaps more so), and mechanical and physical concepts are as human as social and linguistic concepts. Without the functionalist move we seem to get nowhere in biology, or psychology! A Cartesian would say the workings of matter (bodies and their interactions) are transparent to the mind, and those of mind, and freedom of will is what messes up our calculations in the latter field. Now we seem to think the working of matter has a deeper explanation which establishes that there are limits to the accuracy of our ordinary notions of matter in explaining the world, and subjectivity and mind seem to be the next targets for the reductionist approach. Animals, of course, Descartes would make biology depend on matter alone, rejecting Aristotelian substantial natures, and so he allows a reductionist approach to various aspects of mind, passions and the like, which was of long standing already, of course, for in fact, animals display these aspects of mind as well as human beings. To prevent the spread of the mechanistic contagion to our deepest selves, rational and immortal as we supposed them to be, the presence of mind in animals had to be denied ever more strenuously. So Hume, who argued most persuasively that we are no more “directly aware” of mental events than we are of physical events, and then Darwin’s evolutionary theory provided overwhelming challenges to the friends of the Real Subjective Self as a fundamental substance.
In all of these reductionist developments, though, biology and chemistry, like, say, ethics, have retained their autonomy. That is, we can speak as though atoms are as low as it goes, stating their chemical properties in terms of the periodic table, without explaining them using subatomic physics, and it is an extremely useful simplification for us to do so. A great deal we need to do and understand can be done and understood (well, in a way) by a chemist without resorting to subatomic theory in physics. The same is true of biologists, who can work in terms of biological notions quite usefully without worrying about how it is that the physical world allows such notions to be applied to it. Ethics, logic and other philosophical interests will no doubt maintain the same sort of independence. But this sort of independence does not seem to have any ontological consequences about the ultimate things making up the world. And we do not need any such consequences. We can always work usefully at a given level of analysis, though diving deeper might be a useful way to map out the limits of our conclusions, or even suggest new ways of conceptualizing the material that makes more sense of the world. We may reach the point where some level of analysis turns out, it seems, to work perfectly, but I don’t see how we can ever know that is not simply due to the limitations of our observational techniques. All the facts we currently know about the world are of this form: The world (really does) present appearances as though this or that idealized conception is realized in it, perhaps with limitations, but nearly enough in certain circumstances we can recognize so that we will not go wrong analyzing things in terms of that idealized conception. I see no reason why this would ever change, even if progress in the sciences continues indefinitely.