More than 50 years ago Wilfrid Sellars challenged philosophers to explain how to reconcile the universe as we ordinarily experience it with what issues from the sciences, especially physics. In 1963’s Science, Perception, and Reality, he wrote:

The philosopher is confronted not by one complex many-dimensional picture, the unity of which, such as it is, he must come to appreciate; but by two pictures of essentially the same order of complexity, each of which purports to be a complete picture of man-in-the-world, and which, after separate scrutiny, he must fuse into one vision. Let me refer to these two perspectives, respectively, as the manifest and the scientific images of man-in-the-world.

Sellars’ exhortation echoes the physicist A. S. Eddington who, in his 1927 Gifford Lectures (subsequently published as The Nature of the Physical World, 1928) had spoken of setting out to write his lectures by drawing up two chairs to two tables.

Two tables! Yes; there are duplicates of every object about me – two tables, two chairs, two pens.

One of them has been familiar to me from earliest years. It is a commonplace object of that environment which I call the world. How shall I describe it? It has extension; it is comparatively permanent; it is coloured; above all it is substantial.

Table No. 2 is my scientific table. It is a more recent acquaintance and I do not feel so familiar with it. It does not belong to the world previously mentioned – that world which spontaneously appears around me when I open my eyes, though how much of it is objective and how much subjective I do not here consider. It is part of a world which in more devious ways has forced itself on my attention. My scientific table is mostly emptiness. Sparsely scattered in that emptiness are numerous electric charges rushing about with great speed; but their combined bulk amounts to less than a billionth of the bulk of the table itself.

Eddington’s first table is at home in Sellars’ manifest image, the picture of the universe that guides our everyday interactions with our surroundings – including the interactions of scientists in their daily lives and in their laboratories. This picture includes our own self-awareness, our impressions of conscious states and the qualities of experience. The second table belongs to the image of the universe we obtain from physics. The difficulty, remarked by both Eddington and Sellers, is to understand how these images are related.

All this comes sharply into focus when you ask yourself how consciousness, a central component of the manifest image, fits into the physical world. Philosophers have not hesitated to provide answers, including

1. Dualism: consciousness is not a physical phenomenon, but something immaterial, which, although perhaps dependent on physical processes, is not reducible to such processes.

2. Materialism: consciousness is an illusion promoted by philosophers and theologians; indeed the manifest image as a whole is nothing more than a fabrication. Only the scientific image is credible.

Do these options – and their many variations – exhaust the possibilities?

Note that both options start with the assumption that mentality – consciousness – is immaterial. The dualist sees consciousness as an add-on to the physical universe. Features of the everyday manifest image incommensurate with physics are assigned to this immaterial domain. For the dualist, there really are two tables, one belongs to your conscious experience of the universe, the other to the physical universe.

The materialist provides an elegant solution to Sellars’ reconciliation problem, but one that flies in the face of what appears most obvious and certain. Our interactions with the universe, including those of the scientist investigating the physical ultimates take place within the manifest image. Throw this out and rational action would be impossible.

So, which will it be: dualism or materialism?

Neither. The key to understanding our place in the universe, the key to reconciling the manifest and scientific image, lies in the idea of reconciliation. Both dualism and materialism presume that the images are irreconcilable. We need not concur.

Easy to say, but what would be required for reconciliation?

First, the idea that the mental and the physical are radically distinct can be rejected. This is not to say that the mental is the physical. It is to say that dividing the universe into mental things – conscious states, for instance – and physical things – physical states – is a source of error. To be sure, mental categories and our manifest acquaintance with everyday phenomena cannot be represented in the vocabulary of physics. But the fact that we cannot translate talk of mental phenomena and their characteristics into the language of physics no more shows that mental occurrences are immaterial than the fact that talk of the Evening Star cannot be translated into talk of the Morning Star shows that the Evening Star and the Morning Star are distinct heavenly bodies. (“They” are in fact Venus.)

The idea that the mental and the physical are “distinct only in conception” was forcefully defended by Spinoza, among others, and more recently by the American philosopher, Donald Davidson. It provides the golden key required to open the door to a reconciliation of the manifest and scientific images.

Second, rather than starting with the idea that the manifest and scientific images are, if they are pictures of anything,  pictures of distinct universes, or realms, or “levels of reality”, suppose you start with the idea that the role of science is to tell us what the manifest image is an image of. Tomatoes are familiar ingredients of the manifest image. Here is a tomato. What is it? What is this particular tomato? You the reader can probably say a good deal about what tomatoes are, but the question at hand concerns the deep story about the being of tomatoes.

Physics tells us that the tomato is a swarm of particles interacting with one another in endless complicated ways. The tomato is not something other than or in addition to this swarm. Nor is the swarm an illusion. The tomato is just the swarm as conceived in the manifest image. (A caveat: reference to particles here is meant to be illustrative. The tomato could turn out to be a disturbance in a field, or an eddy in space, or something stranger still. The scientific image is a work in progress.)

But wait! The tomato has characteristics not found in the particles that make it up. It is red and spherical, and the particles are neither red nor spherical. How could it possibly be a swarm of particles?

Take three matchsticks and arrange them so as to form a triangle. None of the matchsticks is triangular, but the matchsticks, thus arranged, form a triangle. The triangle is not something in addition to the matchsticks thus arranged. Similarly the tomato and its characteristics are not something in addition to the particles interactively arranged as they are. The difference – an important difference – is that interactions among the tomato’s particles are vastly more complicated, and the route from characteristics of the particles to characteristics of the tomato is much less obvious than the route from the matchsticks to the triangle.

This is how it is with consciousness. A person’s conscious qualities are what you get when you put the particles together in the right way so as to produce a human being.

Although he would not agree, Eddington’s “familiar” first table is his second table. Eddington and the rest of us understand ourselves as inhabitants of the manifest image. The scientific image tells us what it is we are understanding.

These matters are discussed more fully in The Universe as We Find It, Oxford University Press 2012.

Image credit: MR McGill