The attempt to eliminate all contingency from nature leads necessarily to a mechanistic viewpoint. In the mechanistic philosophy of the 18th century – represented in science by Isaac Newton, the bare idea of necessity was elevated to an absolute principle. It was seen as perfectly simple, free from all contradiction, and with no irregularities or crosscurrents.

The idea of the universal lawfulness of nature is profoundly true, but a bare statement of lawfulness is insufficient. What is necessary is a concrete understanding of how the laws of nature actually operate. The mechanistic outlook necessarily developed a one-sided view of the phenomena of nature, reflecting the actual level of scientific development at the time. The highest achievement of this view was classical mechanics, which deals with relatively simple processes, cause and effect, understood as the simple external action of one solid body upon another, levers, equilibrium, mass, inertia, pushing, pressing, and the like. Important as these discoveries were, they were clearly insufficient to arrive at an accurate idea of the complex workings of nature. Later on, the discoveries of biology, particularly after the Darwinian revolution, made possible a different approach to scientific phenomena, in line with the more flexible and subtle processes of organic matter.

In classical Newtonian mechanics motion is treated as something simple. If we know at any given moment what different forces apply to a specific moving object, we can predict exactly how it will behave in the future. This leads to mechanistic determinism, the most prominent exponent of which was Pierre Simon de Laplace, the French 18th century mathematician, whose theory of the universe really is identical to the idea of predestination present in several religions, notably Calvinism.

In his Philosophical Essays on Probabilities, Laplace wrote:

An intellect which at any given moment knew all the forces that animate Nature and the mutual positions of the beings that comprise it, if this intellect were vast enough to submit its data to analysis, could condense into a single formula the movement of the greatest bodies of the universe and that of the lightest atom: for such an intellect nothing could be uncertain; and the future just like the past would be present before our eyes.[12]

The difficulty arises from the mechanistic method inherited by 19th century physics from the 18th century. Here necessity and chance were regarded as fixed opposites, the one excluding the other. A thing or process was either accidental or necessary, but not both. This method was subjected to a searching analysis by Engels in The Dialectics of Nature, where he explains that the mechanistic determinism of Laplace inevitably led to fatalism and a mystical concept of nature:

And then it is declared that the necessary is the sole thing of scientific interest and that the accidental is a matter of indifference to science. That is to say: what can be brought under laws, hence what one knows, is interesting; what cannot be brought under laws, and therefore what one does not know, is a matter of indifference and can be ignored. Thereby all science comes to an end, for it has to investigate precisely that which we do not know. It means to say: what can be brought under general laws is regarded as necessary, and what cannot be so brought as accidental. Anyone can see that this is the same sort of science as that which proclaims natural what it can explain, and ascribes what it cannot explain to supernatural causes; whether I term the cause of the inexplicable chance, or whether I term it God, is a matter of complete indifference as far as the thing itself is concerned. Both are only equivalents for: I do not know, and therefore do not belong to science. The latter ceases where the requisite connection is wanting.

Engels points out that such mechanical determinism effectively reduces necessity to the level of chance. If every trifling occurrence is of the same order of importance and necessity as the universal law of gravity, then all fundamental laws are on the same level of triviality:

According to this conception only simple, direct necessity prevails in nature. That a particular pea-pod contains five peas and not four or six, that a particular dog’s tail is five inches long and not a whit longer or shorter, that this year a particular clover flower was fertilised by a bee and another not, and indeed by precisely one particular bee and at a particular time, that a particular windblown dandelion seed has sprouted and another not, that last night I was bitten by a flea at four o’clock in the morning, and not at three or five o’clock, and on the right shoulder and not on the left calf – these are all facts which have been produced by an irrevocable concatenation of cause and effect, by an unshatterable necessity of such a nature indeed that the gaseous sphere, from which the solar system was derived, was already so constituted that these events had to happen thus and not otherwise. With this kind of necessity we likewise do not get away from the theological conception of nature. Whether with Augustine and Calvin we call it the eternal decree of God, or Kismet as the Turks do, or whether we call it necessity, is all pretty much the same for science. There is no question of tracing the chain of causation in any of these cases; so we are just as wise in one as in another, the so-called necessity remains an empty phrase, and with it – chance also remains what it was before.[13]

Laplace thought that if he could trace the causes of everything in the universe he could abolish contingency altogether. For a long time, it appeared that the workings of the entire universe could be reduced to a few relatively simple equations. One of the limitations of the classical mechanistic theory is that it assumes that there are no outside influences on the motion of particular bodies. In reality, however, everybody is influenced and determined by every other body. Nothing can be taken in isolation.

Nowadays the claims of Laplace seem extravagant and unreasonable. But then, similar extravagances are to be seen at every stage in the history of science, where each generation firmly believes itself to be in possession of the “ultimate truth”. Nor is this entirely mistaken. The ideas of each generation are indeed the ultimate truth, for that period. But all that we are saying when we make such assertions is: “This is as far as we have got in understanding Nature, with the information and technological capabilities we currently possess.” Therefore, it is not incorrect to claim that these truths are absolute for us at this moment in time since we can base ourselves on no others.

  1. Quoted in Stewart, I. Does God Play Dice? pp. 10-2.

  2. Engels, F. The Dialectics of Nature, pp. 289-90.