31.2. Russellian Monism

There are strong echoes of Hume's 1.4.4 in contemporary philosophy. “How can there be a world in which objects have primary qualities, but no secondary qualities?” ask J.J.C. Smart (1963), D.M.Armstrong (1961), and Simon Blackburn (1993), all seeing the question as a prob­lem for the scientific realism they would otherwise like to defend.

As Smart and Armstrong develop the problem, a critical aspect of it is that science seems to ascribe to objects relational properties only. Electrons have mass, charge, and spin, says Smart, but these are all relations—“What is the electron in itself?” (72). And Armstrong says, “If we look at the properties of physical objects that physicists are prepared to allow them such as mass, electric charge, or momentum, these show a distressing tendency to dissolve into relations that one object has to another” (1968, 74—75). But if something has relational properties, must it not have intrinsic properties, too?

Blackburn raises a distinct but similar problem. In his case, the problem is that science ascribes to objects nothing but dispositional properties (255). But if things have dispositional properties, must they not also have categorical properties to ground the dispositions? The concern looms that the worldview of science is at best incomplete and at worse inconceivable.

None of these authors believes that the problem they raise is insoluble. They believe either that a world of nothing but relations or dispositions is possible after all or, if not, that purely physical properties can fill the apparent gaps. But some recent authors have not been so san­guine. Under the banner “Russellian Monism,” they advocate a cluster of views I enumerate as follows, guided by Alter and Nagasawa 2015b:

(1) Physics tells us only about the structural properties of the world.

(2) Nothing can have relational and dispositional properties alone.Things with relational prop­erties must also have intrinsic properties, and things with dispositional properties must also have categorical properties.

(3) Therefore, there must be properties of external things unknown to physics. Because they are unknown to physics, they are sometimes called inscrutables, even though on some views we are acquainted with them as properties of our own percepts, which according to Russell are the only intrinsic properties we know.

Tenet (1) is defended in various of the writings ofBertrand Russell from 1927 on.⁴ It is defended by many philosophers of science today under the name “epistemic structural realism” (Ladyman 2016).

The twin tenets in (2), though contested, are defended by many metaphysicians. There is a tendency in discussions of our topic to roll them together: dispositional properties get equated with relational properties and categorical properties with intrinsic properties.The equations are mistaken.There are relations that are not dispositions, even if they imply dispositions: I am seated at my desk, and that is something that is occurring right now. Conversely, there are dispositions that are not relational; sugar has the disposition to dissolve in water, and that might be true even of a cube of sugar that was the only thing in the universe. Moreover, the thesis that dispositions must have a categorical basis is sometimes equated with the thesis that dispositions must have an intrinsic basis, and that equation is also mistaken. An object might be visible right now because it is placed against a dark background and bathed in bright light—to say that is to ground a disposition in categoricals, but not in intrinsics.

The dependence of dispositions on categoricals is typically held as a thesis of grounding: any disposition of a thing must be grounded in a categorical property, as the disposition to roll if released on a hill is grounded in roundness.The dependence of relations on intrinsic properties could also be advanced as a thesis of grounding, as it was by Leibniz (relations are grounded in qualities of the relata), but it need not be. One could hold that the relata of any relation must have intrinsic properties just because everything must have them—no concrete thing can have relational properties only.

If tenets (1) and (2) are both admitted, tenet (3) is the almost inevitable result:⁵ there must be properties unknown to physics.What might they be? Alter and Nagasawa canvass four candidates. (a) They might be phenomenal properties or qualia, such as we experience in seeing a splash of red or hearing the F above middle C. (b) They might be proto-phenomenal properties, properties that are not themselves phenomenal, but are capable of compounding somehow into phenomenal properties. (c) They might be properties that are neither mental nor physical, but neutral. (d) They might be physical properties of a special sort, unknown to physics but physical nonetheless.

Option (a) verges on panpsychism, a view often thought extravagant, but taken seriously by some contemporary philosophers, including David Chalmers (1996, 297—299) and Galen Strawson (2019). Whether it would really be panpsychism depends in part on the relation of qualia to consciousness. If qualia are either modifications of conscious states or items that exist only as objects of conscious states, then consciousness would have to be present at a very fun­damental level in the physical world.An advantage sometimes claimed for this possibility is that it not only provides us with the intrinsic properties missing from the worldview of physics, but makes it easier to comprehend how consciousness could arise in complex organisms—it is already present in some form in the basic building blocks.⁶

Option (b), proto-phenomenal properties, is advanced by Chalmers (1996, 127 and 154). It is hard to say much about it until it is more explicitly worked out. Option (c), neutral properties, has some overlap with the view Russell espoused under the name “neutral monism.” He said that the properties we are aware of in introspection are by themselves neither mental nor physi­cal, but are properties some constellations of which constitute minds and other constellations of which constitute matter.This is one reason why Russellian Monism is so called, but it need not be developed in this direction.

It should now be clear in what ways Russellian Monism is and is not an echo of Hume.“The modern philosophy” and modern physics both describe a world that has primary or structural qualities only, and Hume and the Russellian Monists both say nothing can be conceived as being like that. For Hume, this is a case of inconceivability^ we can form no conception of the modern philosopher’s world, no “just idea” of it. For the Russellian Monists, it is a case of inconceiv­ability^ we cannot see how a world could exist merely as described by science—all relation and no quality, all disposition and no basis, all form and no filling—or perhaps more strongly, we positively see that things could not be that way. The Russellian Monists fix the problem by positing properties not found in physics textbooks—perhaps phenomenal properties, akin to the secondary qualities Hume says are not there; perhaps inscrutable physical properties, of which Hume would say we have no idea because we have no resembling impression.