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Tallis in Wonderland

‘The Laws of Nature’

Raymond Tallis gazes into the gap between nature’s habits and the laws of science.

A little while back I touched on the ‘laws of nature’ in the course of a defence of free will (‘The Mystery of Freedom’, Issue 140). I argued that if we were entirely subject to such laws, then neither the experimental science by which they were discovered nor our capacity to exploit them through technology would be possible.

Our undeniable ability to manipulate states of matter inside scientific laboratories in pursuit of knowledge of its general properties, and to apply that knowledge outside of the laboratories in support of our agency, are perhaps the most striking expressions of the way in which we humans transcend the material world. But ‘the laws of nature’ (so-called) deserve more attention than I gave them in that piece on free will.

Horses and Riders

Let’s begin with the common notion that the laws of nature have regulative powers. Are they, as the philosopher Tim Maudlin described them, ‘pushy explainers’? And, if they are pushy, are they pushy in the sense of being the engine of change in a universe that would otherwise be inert; or do the laws merely have directive powers, acting as rails along which what happens is channeled? Not the horses making things happen, but only horse-riders guiding them this way rather than that. As Helen Beebee asked, wittily mocking this latter idea, are the laws of nature “‘out there’, prior to and watching over matters of fact to make sure they don’t step out of line”? (‘The Non-Governing Conception of Laws of Nature’, Philosophy and Phenomenological Research, 2000). However, the difference between horse and horse-rider is not clear cut. Even if the laws mandate one trajectory rather than another (riders) instead of ensuring that there is a trajectory at all (horses), some pushiness is still required to ensure that path A is taken rather than path B.

The need for pushiness to keep the universe on the move presupposes a default state of stasis. The sense that things have to be made to happen by laws may be connected with the freezing of the flow of process when the world is sliced into discrete facts corresponding to a succession of instantaneous states. Contrariwise, the idea of laws as mere guides seems to assume that dynamism is already built into the order of things and nothing is required to maintain change. But what these two views have in common is the suggestion that the laws somehow act upon the stuff of nature from outside it. The fundamental intuition that they have legislative authority is that there could be no regularity without regulation: that something is needed to maintain the order of an unfolding nature so that the world goes round rather than all over the place.

However, both alternatives – horse or rider – require us to embrace the dubious notion of the laws of nature as having or being powers in themselves. Such a conception of ‘pushy’ or ‘coercive’ or ‘constraining’ laws may be a projection into the material world of our experience of engaging with it. It is, after all, in relation to the fulfilment of our intentions that we experience universal laws as both local constraints and enablers. Thus understood, laws are a ‘quasi-agency’ – a distant echo, perhaps, of the idea of a supernatural, omnipotent God running the universe.

A Taste of Explanation

We are close to an argument that has generated a large philosophical literature since David Hume first examined the idea of natural necessity in the eighteenth century. Beebee frames this argument well by contrasting the two main views as to what laws of nature are: on the one hand, as ‘mere generalisations of the broadest and most accurate kinds’, expressing how things just happen to be; on the other hand, ‘relations of necessity’, describing how things must be, because the laws require them to be so. The former formulation sees the laws as merely reflecting the regularity of patterns of events and how they are connected. That is to say, the laws of nature do not shape what happens but are simply the shape of what happens. By contrast, laws as ‘relations of necessity’ are invoked to explain how that regularity is secured. The expectation of finding an explanation of nature’s regularity is the result of extrapolating to the whole of things the belief that every individual thing happens for a reason – that nothing ‘just happens’.

If we downgrade the laws of nature to mere reliable regularities, they come to look less like explanations than descriptions – however authoritative, accurate, and general – of what just happens to happen. If laws-as-mere-regularities-rather-than-regulators sometimes seem to taste like explanations, it’s when they’re invoked to account for particular events covered by them – as when we explain the trajectory taken by a cannonball using universal laws of motion – or when a lower order law is revealed to be a local manifestation of a higher order law – as when Boyle’s law connecting the pressure and volume of a gas is seen to be a manifestation of the kinetic theory of gases. The arrow of what feels like explanation goes from particular events to general laws, and from less general laws to more general laws: ‘things go this way on this occasion because this is how all things of this class go’. At that point, however, the taste of explanation disappears. So even if connecting particular events with descriptive laws counts as ‘explanation’, it’s an explanation that eventually hits the buffers of ‘this is just how things are’. The laws are, nevertheless, reassuring, because they flag up something stable underlying all the change, most explicit in the great conservation laws, culminating in the law of the conservation of mass-energy.

The least metaphysically burdened account of laws, then, sets aside the idea of them as principles of material necessity built into the universe, driving or otherwise regulating change, in favour of their being the most general and reliable accounts of nature’s behaviour. Such regularities are not required to be maintained by an independent regulator. The natural world is not the obedient servant of a legislative master. Instead of having power – a kind of mindless agency – built into them, the laws of nature reflect a universal propensity by which the uniformity of patterns of change can be relied upon to look after itself. The only obligation is that things should continue to behave as they can be seen to behave, so that, just as they unfold on a particular occasion, so they unfold on all similar occasions. Even ‘obligation’ is too strong a term. It is better perhaps to settle for ‘things just carrying on in a uniform way’. Necessity is verbal, logical, or theological; as such, it has no place in grown-up philosophy of science.

The Habits of Nature

It may be better, therefore, to speak of the mere ‘habits’, rather than ‘laws’, of nature. But although the term ‘habits’ is unburdened with dubious notions of legislative authority, it may still seem unsatisfactory. It is rather homely and low-key, and seems to do scant justice to the unfolding magnificence of the universe. What’s more, a habit is something that we typically think of as being acquired, and equally as capable of being set aside or overcome. Clearly, this does not apply here: its regularities are not something the universe can just kick aside or grow out of. Nevertheless, I cannot find a term that better captures a uniformity in nature that is not mandated from without and is reflected to differing degrees in the laws of science. If there were a better term, I would happily embrace it. Meanwhile ‘habit’ will have to punch above its usual weight.

Renaming laws ‘habits’, however, makes them no less intransigent. There is perhaps a less daunting interpretation of the unbreakability of the law-like habits of nature: laws reflecting habits must be unbroken to qualify as laws. A law that proves not to be exceptionless will lose its standing as a law.

There is not much comfort to be had here. Firstly, the principle of apparent unbreakability itself remains unbroken. Secondly, the regime of the discarded law is no more forgiving than that of its successor laws. A Newtonian world-picture is not noticeably less constraining than a more accurate Einsteinian one.

Science or Nature?

That the laws of science are always being revised raises fundamental questions about their status. An ‘anti-realist’ view of science argues that, while its laws have instrumental value (they help us do things), they do not reflect the intrinsic nature of the world. As the American philosopher Hilary Putnam pointed out, however, this view of science would make its spectacular success in predicting and manipulating the material world a ‘miracle’ (Mind, Language and Reality, 1975). That is why I believe that, as science evolves over time, and one set of laws (with accompanying forces, entities, models, theories, etc) is replaced by another more accurate and of a wider scope, that science is getting ever closer to nature itself. Irrespective of whether this optimistic story – to some degree anti-realist about the past of science, and realist about its ultimate future – is true, it reminds us of something of crucial importance: throughout the history of science there has been a gap between the habits of nature (which do not change) and the laws of science (which do). This gap is hidden in the phrase ‘the laws of nature’, which seems to conflate nature’s permanent habits with science’s changing laws.

The gap between the habits of nature and the laws of science is also highlighted by the division of science into disciplines with different areas of interest and scales of attention, each with their own laws. Nature itself, unlike science, is not biological, biochemical, or chemical; or rather, it does not separate these aspects of itself. On the other hand, the suggestion that all the disciplines with their special laws will eventually be superseded by a physics evolving towards a Theory of Everything in which the habits of nature and the laws of science are one, is deeply problematic – the most obvious problem being accounting for the emergence of the rich, heterogeneous world that surrounds us from out of the characterless entities to which fundamental physics boils it down.

Time to return to our starting point: the compatibility of law-like nature with the exercise of freedom by human agents. The clue lies in the gap between nature’s habits – which we must assume have not changed, at least in the short time since human beings first became scientists – and the changing laws of science. The latter belong to a virtual space outside of nature, created and occupied by humanity. It is from this space that the habits of nature are available to be exploited to achieve our ends. The intransigent habits of nature – necessary, after all, for our actions to have their desired consequences – may therefore be more friendly to the idea of free action than might first appear. And so we return to the place where this article’s journey began.

Raymond Tallis’s latest book, Freedom: An Impossible Reality will be published in September 2021.