From Physics to Metaphysics and Back Again

J. J. C. Smart

Physics is now taken to be the study of the laws of nature. Because of the theory of the chemical bond it can be taken as encompassing much of chemistry. Physics is universal: the laws of physics contain no exceptions, though they may be approximations.

Thus Newton’s laws of motion, despite special relativity, are a good approximation for velocities small compared with the velocity of light. Special relativity is Lorentz invariant whereas Newtonian dynamics Galilean invariant. Maxwell’s electromagnetism is already Lorentz invariant. Einstein’s equations improved on Newton’s and kept Maxwell’s, whereas previously people had kept Newton (by postulating an aether which was supposed to give a single frame of reference) and messed about with Maxwell. The kinematics of Special Relativity is best explained by a four-dimensional Minkowski space, in which the Lorentz transformations come out as a rotation of axes. (Indeed the Newtonian transformation is odd in that one rotates the time axis without rotating the space axes.) Thus the new theory provides better explanations; but this is because the old laws provided only approximations, not because they had exceptions. It is still a law, not merely a generalization, that low velocities match Newtonian predictions approximately.

In biology, on the other hand, there can be exceptions. Biology (even genetics) contains generalizations, not laws. A biologist can live with exceptions, even to Mendel’s so-called laws. My 1959 paper “Can biology be an exact science?” was written when I was at the University of Adelaide and I attended a biological discussion group and the title was suggested by the then Professor of Zoology W. P. Rogers.1 In fact the paper was better liked by the biologists than by philosophers. Generalizations are things that one can live with despite exceptions, whereas laws do not have exceptions — if something has an exception it is not a law, although it can be treated as useful in certain conditions. This is how I interpret Rutherford’s slightly unkind remark that “All science is either physics or stamp collecting”. This is not to disparage biology, geology and other applied sciences. Physics is cosmological and biology is terrestrial, since generalizations about life on planets or distant stars might have to be considerably different from those about life on earth. In exobiology we would expect the evolutionary trees to be very different in ways other than in mere numerical differences. I would like to say that biology is to physics much as electronic engineering or wiring diagrams are to electromagnetism. Engineering often contains mistakes. High tension lines sometimes fail, and so on. But these are not exceptions to the laws of electromagnetism; the errors arise from exceptions to generalizations, not laws.

Biology contains explanations of biological phenomena, but this is not a matter of direct deduction from natural laws. It is, rather, by deduction from natural laws plus generalizations of natural history. But in any discipline these generalizations should be plausible in the light of total science. To take another example, Cartesian dualism and its modern successors should be seen as very implausible. Is it likely that there should be complicated (very complicated) laws or generalizations relating the physical structure of the human or animal brain to non-physical consciousness?

What, then, about metaphysics? I would like to say that good metaphysics is an extension of physics in the direction of plausibility in the light of total science. This is because the scientific method has proved to be the best way of acquiring knowledge about the universe. Sometimes, admittedly, metaphysics strays towards the other end of the plausibility spectrum from physics. But in good metaphysics we should still keep an eye on plausibility in the light of total science.

The etymology of the term “metaphysics” is interesting. There is a good deal of complicated scholarship about it, but near enough the story is that “metaphysics” is so called because it refers to enquiries such as those in which Aristotle engaged in “next to the physics”. In the Physics, Aristotle discussed the natural world and “metaphysics” came to refer to the sorts of problems that Aristotle discussed in his “Next to the physics” — like the next book on the shelf. Eventually this bibliographical classification came to refer to the wider sort of investigations which Aristotle discussed in his “Next to the physics”, and then of course its connotation was extended due to scientific progress.

Perhaps then we could think of good metaphysics as the conjectural end of physics. Commonly this usage is even extended further to really wild theories: I have already mentioned mind-body dualism. Another example may come from Eddington, who was (with Schwartzchild) one of the two outstanding astronomers of the twentieth century. In his popular book The Nature of the Physical World, he remarks that “The whole subject-matter of exact science consists of pointer-readings and similar indications”.2 This is to neglect the fact that an instrument such as an ammeter or voltmeter has to be calibrated and this requires an application of the theory of the instrument. And beyond that, Eddington was himself aware of the immensity of our wonderful universe, and that to reduce it to actual and possible observations is really quite mad.

Of course, Eddington was not only a great astronomer and physicist but a writer of beautiful prose, and so should not here be taken au pied de la lettre. Similarly, we could extend this literary generosity to F. P. Ramsey’s remark, in the Epilogue to his Foundations of Mathematics, that his picture of the world is drawn in perspective: “The foreground is occupied by human beings and not like a model to scale”.3 Charitably interpreted, he is not really implying that astronomy is just a description of a small part of the course of human and possibly animal sensation. Of course that leads to phenomenalism and free-standing contrary-to-fact conditionals. (This got effectively knocked on the head by W. V. Quine’s criticisms of modal logic.4. This phenomenalism is anthropocentric, or at least psychocentric, and is not plausible in the light of total science.

The absolute idealism of F. H. Bradley and various lesser minds was somewhat different and its ancestry from physics had finally been lost. Bradley said that metaphysics is finding bad reasons for what we believe on instinct. G. A. Campbell, my professor at Glasgow when I was an undergraduate there, followed this “instinct” to an even greater degree. He carried Bradley even further, aided by bad logic and influenced particularly by the bad logic in Bradley’s Note A to the second edition of his Appearance and Reality.5 In saying that Campbell was carried along by bad logic, I do not wish to suggest that he was not a very fine and dedicated philosopher, especially when he descended from the noumenal to the phenomenological and wrote much like any other philosopher. Not that I have always agreed with him, for example on the subject of free will. But in his book Scepticism and Construction6, he out-Bradleyed Bradley.

In fact, his philosophy in the end is comparable to the Advaita Vedanta (nondualism) of ancient and medieval Indian philosophy. In the Advaita there was a denial of plurality. In the Brihad Aranayaka Upanishad this is put forward forcefully as follows:

For where there is a duality (dvaita) as it were, there one sees another, there one smells another; there one hears another; there one speaks to another; there one understands another. Where verily everything has become just one’s own self, then whereby would one smell? Then whereby and whom would one see? Then whereby and whom would one hear?

Lo, whereby would one understand the understander?7

Here the error comes not from bad logic, as with Campbell, but from mysticism. Looking at things from the methodology of plausibility in the light of total science, it is better to think of mysticism as arising from reversion to something like the lizard brain, not from getting into a higher state.

If for whatever reason we find ourselves stating something incompatible with what we know of physics, we should quickly go back again.


1 Smart, J. J. C. 'Can Biology be an Exact Science?', Synthese Vol. 11, (1959), pp. 359-368.

2 Eddington, A. The Nature of the Physical World, (Cambridge: Cambridge University Press, 1928), p. 252.

3 F. P. Ramsey, Foundations of Mathematics, ed. R.B. Braithwaite, K. Paul, Trench, Trubner, London UK and Harcourt Brace, New York NY, 1931, p.291.

4 W.V. Quine, “Three grades of modal involvement”, The Ways of Paradox, Random House, New York NY, 1966.

5 F.H. Bradley, Appearance and Reality: A metaphysical essay, Clarendon, Oxford UK, 1959.

6 G.A. Campbell, Scepticism and Construction: Bradley’s sceptical principle as the basis of constructive philosophy, G. Allen & Unwin, London UK, 1931.

7 I quote from the translation by R.E. Hume, The Thirteen Principal Upanishads, second edition revised, Oxford University Press, Oxford UK, 1968, p.101.