Reduction Redux

Reduction Redux

I have been too harsh on reductionism; it really isn’t such a bad thing, correctly understood. It all depends on the kind of reduction. Materialist reduction has given it a bad name, because it is just not plausible (as typically formulated anyway). The OED defines “reduce” as “make or become smaller or less in amount, degree, or size”. That would apply to materialism because it makes the world smaller by reducing everything to the physical: one thing is less than two things. But it also reduces the mind to something it is not—and that is the problem, not the sheer reduction. Even if there were as many kinds of matter as kinds of mind, or even more, it would still be objectionable. If the materialist announced that there are twice as many kinds of mental state than we thought, because of the greater variety of physical states correlated with mental states, that would not lessen its implausibility. This would expand not reduce the quantity of mental states, but the trouble is that the nature of mental states is not capturable by physical states. Reduction is okay; bad reduction isn’t. Reductionism is not intrinsically bad. We already knew this: nobody recoils at reducing water to H2O or heat to molecular motion, even though we have reduced the world from two natural kinds to one in each case. Newton reduced terrestrial and celestial motion to a single kind of motion (with tidal motion thrown in), thereby reducing the number of forces in the world; but that is fine because his theory is sound. It is the same for Darwin’s reduction of animal species to animal varieties, thus reducing the number of ways animals can differ; we don’t need another explanation to explain the origin of species. One is a special case of the other. Reductions can be good, illuminating, and true. Reductionism is perfectly acceptable in its place. One man’s reductionism is another man’s theoretical unification.

There are some harder cases. Was Berkeley a reductionist? True, he reduced the number of basic entities in the world from two to one (matter and mind); but he introduced God into the empirical world and rejected mechanism as a theory of mental causation. He expanded ontology while also contracting it. One might object that his theory is false to the nature of matter, but that is not the fault of his reductionism per se. The trouble with reductive idealism is not that it is reductive but that it doesn’t correctly capture what it tries to reduce. What if he tried to reduce everything, including us, to the contents God’s mind? That is highly reducing, but it doesn’t strike us as failing to do justice to our nature, as materialism does. For the contents of God’s mind can be arbitrarily expansive; putting us in there doesn’t do violence to our evident nature. Is Russell’s theory of descriptions reductive? Yes, in that it replaces definite description with quantifiers, thus reducing the number of primitive expressions; but it doesn’t elicit the response that it is untrue to the meaning of “the”. By contrast, Thales’ “All is water” seems incredibly reductive, because so homogenizing—while “All is atoms” seems quite reasonable. Did we reduce Hesperus to Phosphorus? Yes and no: we got rid of one thing by identifying it with another, but it would be weird to say we reduced Hesperus to Phosphorus (why not the other way about?). Did we reduce stars (some of them) to planets? Did we reduce the Moon to a barren satellite of Earth? Is the true justified belief theory of knowledge a reduction of knowledge? Does the truth conditions theory of meaning count as a reduction of meaning? What about the image theory? Is possible worlds semantics a reduction of modal notions? Etc. These questions seem futile; the only issue is whether the theories in question are plausible. Say what you like about reduction; truth is what matters. The whole idea of reductionism seems empty and pointless. Is it good or bad? It depends, and anyway the real question is independent of that. The idea of reduction should not play a role in the relevant discussions. Certainly, it is not inherently a derogatory term. There are nice ones and nasty ones, that’s all.

What about the idea of irreducible entities? Suppose I say that colors are irreducible: they are not physical properties or dispositional properties or mental properties, but simple primitive properties in their own right. They have no analysis, no hidden structure, no real essence—they are what they are and no other thing. Isn’t that pretty reductive? I am denying them complexity, depth, an underlying nature. I am saying they are lessthan other properties, not as complicated, more one-dimensional. What if colors were traditionally regarded as like natural kinds with a hidden real essence—wouldn’t it seem reductive to say that they are no such thing but entirely superficial? Wouldn’t that be received as denying them their due as natural kinds? What if we said the same thing about water? It depends on expectations. If I said that colors are like primitive simple sensations with no further reality than their appearance, wouldn’t that sound reductive—surely colors have some sort of hidden nature. How do they become attached to objects along with size and shape? Don’t they need something to tie them down to material things, as physical properties and dispositions do? Irreducibility claims can sound pretty reductive in their way, because they deny depth.[1]

Here is a final tricky case. Suppose I grow suspicious of the soul as depicted in religious discourse (immaterial, immortal, possibly disembodied, supernatural). I propose that the soul is reducible to the person, construed as a psychophysical entity or as ontologically primitive. Then someone comes along and argues that the person is really reducible to psychological connectedness, calling himself a reductionist about persons.[2] But then this is deemed suspect because too divorced from the animal nature of persons; it is proposed that human beings are (just) animals of a certain biological species. And then it is suggested that even the concept of animal is too divisive; better to speak of “organisms” so that we don’t draw too sharp a line between animals and other living beings (worms, amoebas, bacteria, plants). But that is thought not quite reductive enough: isn’t an organism reducible to a collection of organs? Thus, the soul is reducible to the organs of the body. Is the concept of reduction doing any useful work here? Isn’t it introducing merely verbal quibbles into the discussion? The real question is whether any of these identifications are true. Asking whether they are “reductionist” cuts no ice. The term has outlived its usefulness. Being a reductionist is neither good nor bad in itself, merely meaningless; similarly, for being an anti-reductionist. It is more rhetoric than ratiocination.[3]

[1] What if I said there is nothing more to the ocean than its surface—a primitive property?

[2] This was Derek Parfit’s own self-description.

[3] And yet it has dominated philosophy of mind for lo these many years. You are either a reductionist or an anti-reductionist. I might be described as a “mysterian reductionist”, but how does that differ from believing that mental states have an unknown nature? It certainly isn’t the same as saying that mental states are less than they seem.