The rise of modern physics and biology yielded a picture of the world that had many philosophers thinking: “Everything is made of the same stuff and operates under the same principles.” Where human beings once had been thought to occupy a separate ontological category, due to our minds and capacity for thought (which led Descartes to declare a “dualism of mind and body”), the discovery of our primate origins and advances in our understanding of neurology and the brain undermined this idea, notwithstanding the cultural and political pushback against evolutionary biology which culminated in the (in)famous Scopes Trial.
In philosophy, this new way of thinking was expressed through the idea of the “unity of the sciences.” If everything ultimately was made of the same stuff (atoms and subatomic particles) and governed by a common set of scientific laws (however one construed them), then we should expect to converge upon a single, unified explanation of the world: the macro will be explained in terms of the micro; the organic in terms of the inorganic; and the social in terms of the psychological, biological, and finally, the physical.
“Reductionism” represented a formalization of this idea. Laws of “higher level” sciences (sociology; economics; political science; psychology; etc.) would be demonstrated as being “equivalent” (however one construed this) to laws belonging to “lower level” sciences (biology; chemistry), culminating in laws of physics. Without getting into the weeds (I discussed it in some detail here), intertheoretic reduction was supposed to be accomplished by way of “bridge laws” which “reduced” the laws of a higher-level science to those of a lower level one, and this required that the “kinds” of each higher-level science be “equivalent” (again, however one construed this) to those of the lower-level ones and ultimately to the kinds one finds in physics.
Jerry Fodor burst this aspirational bubble in 1974, with the publication of his paper, “Special Sciences (Or: the Disunity of Science as a Working Hypothesis).” He observed that the relevant kind-equivalencies could never be established because the kinds one finds in higher-level or “special” sciences are multiply-realizable. To take just one example, currency — a kind in economics — can be “realized” in paper, metals, gemstones, electronic signals, etc., and the long, diverse disjunction of material kinds this involves — “paper or metals or gemstones or electronic signals” — is not identical with or equivalent to any kind that one might find in a lower-level science, and certainly not in physics. Where metaphysical unity goes, explanatory unity follows, since where there can be no reduction of kinds there can be no reduction of laws, and where there is no reduction of laws, there is no reduction — and thus, no unity — of explanation.
Fodor’s critique was directed towards a specific version of the reductionist thesis, and as one might expect, resistance came in the form of philosophers proposing one variation or another that purported to get around the objections. Some denied the necessity of bridge laws or reconstrued them in such a way as to avoid Fodor’s critique. Others advanced non-reductive versions of Materialism. Regardless, it all quickly descended into a fog of endless variations and backs-and-forths (as philosophical disputes are wont to do), until the forest was lost for the trees. As a result, the expectation that metaphysical monism and explanatory unity would prevail largely remained intact, albeit more vaguely and tacitly. What not enough philosophers realized, however, is that the Unity Project had already been dismantled a decade before Fodor’s “Special Sciences” and in much more general terms that did not depend on any particular version of Reductionism; specifically, by Wilfrid Sellars, in his paper, “Philosophy and the Scientific Image of Man” (PSIM) (1963).
I’ve already gone into some detail on PSIM, so a sketch will suffice. Sellars describes two fundamental “Images” (i.e. pictures; conceptions) of “man-in-the world”: the “scientific” and the “manifest.” The Scientific Image describes the world in entirely quantitative terms, in which we figure purely as organisms, while the Manifest Image describes the world in both quantitative and qualitative terms, in which we also figure as persons with aims and ends and points of view and all the things that follow. At the center of the Manifest Image are people and the social institutions, spaces, and forms of life that we create and which are defined by individual and collective goals that are only articulable in terms of values and ends. This means that while explanations in the Scientific Image are rigorously and exclusively causal, any account of the goings-on of people and institutions in the Manifest Image is going to be teleological and axiological. As Sellars puts it:
[T]he conceptual framework of persons is the framework in which we think of one another as sharing the community intentions which provide the ambience of principles and standards (above all, those which make meaningful discourse and rationality itself possible) within which we live our own individual lives.
To think of a featherless biped as a person is to think of it as a being with which one is bound up in a network of rights and duties. From this point of view, the irreducibility of the personal is the irreducibility of the ‘ought’ to the ‘is’.
That values and purposes cannot be reduced to facts and causes is well-understood, and modern science has long excluded teleology from its explanatory frameworks, with the biological treated as teleonomic rather than genuinely purposeful. In contrast, the teleological is not separable from the personal or the social, but rather, fundamental to them. One can give an account of the heart or the liver entirely in terms of physiology and evolutionary theory, without ascribing literal purposes to these organs, but for any credible account of people’s actions or social institutions, values and ends are basic, unavoidable, and irreplaceable. Indeed, at one point in the paper, Sellars warns against the sort of “piecemeal” reductions of bits of the Manifest Image to the Scientific Image that are so common in analytic philosophy; in formulas like: “The mind is the brain” or “mental states are neurological states.”
Given the irreducibility of the social to the physical, of values to facts, and of purposes to causes, we have essentially two choices. We can double down on the Unity Project and insist that the social, axiological, and teleological don’t exist or are “illusions” or some other such thing, a category of response known as “Eliminativism,” or we can accept a fundamental disunity in explanation and “being” and embrace metaphysical and explanatory pluralism.
Though the interpretation of Sellars’ paper is fraught and has resulted in warring camps — he is claimed as an inspiration by eliminativists and pluralists alike — I am firmly on the pluralists’ side, taking my lead both from this line from PSIM’s final paragraphs — “[T]he conceptual framework of persons is not something that needs to be reconciled with the scientific image, but rather something to be joined to it” — and from Sellars’ invocation of stereoscopes, several pages earlier:
[T]he most fruitful way of approaching the problem of integrating theoretical science with the framework of sophisticated common sense into one comprehensive synoptic vision is to view it not as a piecemeal task—e.g. first a fitting together of the common sense conception of physical objects with that of theoretical physics, and then, as a separate venture, a fitting together of the common sense conception of man with that of theoretical psychology—but rather as a matter of articulating two whole ways of seeing the sum of things, two images of man-in-the-world and attempting to bring them together in a ‘stereoscopic’ view.
A stereoscope is a device in which two separate images are combined to form a single one, and the idea here is that a complete picture of the world can only be accomplished by combining its elements, since they cannot be assimilated to one another. It seems unlikely, then, that Sellars was an eliminativist or that his view is sympathetic to Eliminativism. The eliminativist “solves” the alleged problem of the irreducibility of the Manifest Image by simply deleting it, which leaves nothing to reconcile. By introducing the metaphor of the stereoscope and by maintaining that a complete picture of the world can only be one in which the Scientific and Manifest Images are brought together, it is clear that Sellars thought absurd the suggestion that the social universe and everything in it doesn’t exist — that there are in fact no persons, states, laws, economies, goods, bads, rights, wrongs, etc. — and believed that one cannot have knowledge of the world, when entire categories of things that demonstrably exist are left out.
The pluralist view doesn’t require us to deny any part of the world and only becomes more compelling when one realizes that philosophers’ resistance to it depends entirely on uniquely philosophical hangups: that pluralism drives us to Dualism or Platonism or other such metaphysical extravagances, because otherwise, we can’t make sense of what minds and thoughts and countries and parking regulations are “made of”; that the fact that these sorts of things are not physical saddles us with “interaction problems” (“How do non-physical persons ride bicycles?”); that lacking unity of explanation, human knowledge is left with no “foundation”; etc.
Fortunately, these hangups have little credible basis — I exposed many of them for the thin stuff that they are, once again, here — and needn’t (and mostly don’t) trouble us. We can only hope that eventually, the philosophers will come around.
