How the laws of physics lie

28 Apr, 2017 at 21:01 | Posted in Theory of Science & Methodology | 10 Comments


Melvyn Bragg and guests — Nancy Cartwright, Mark Buchanan and Frank Close — discuss if there are any Laws of Nature. And if so — are they really ‘facts of life’?


  1. Lars, I think that you have an important substantive point, but Bragg’s guests seem to share a view that the laws and facts of physics are generally true to physicists’ findings, and thus may be regarded as ‘scientific’ in a sense that the ‘laws’ and ‘facts’ of economics are not.

    Bragg himself seems to share some common confusion about the nature of science, but at least he is engaging on the topic. Would that the more influential economists would do the same!

    Widening your topic, I think we can split ‘experts’ into nerds, pseuds and broad. We used to have institutions called ‘universities’ that aimed to turn out broad experts, who understood their chosen field within the broadest context. We also have nerds, who can work efficiently within a discipline but have a limited understanding of the broader context. In addition, we also have some pseuds, who – perhaps under financial or career pressure – are careless about the broader implications of what they are doing: perhaps ‘above their pay grade’. It seems to me that the balance has shifted for the worse, and is worse in economics than in any science. Be that as it may, it is not so much that Physics lies, as that pseudo-Physicists lie or nerd-Physicists misrepresent it. This is not unique to Physics, and the solution may be to engage more with broad experts, including Physicists.


    • Thanks for your comments Dave.
      It was indeed a pity that Nancy Cartwright didn’t get the chance to elaborate her views more fully in the program. One of her early books — which has influenced my own take on the issue — published more than 30 years ago –was the pathbreaking “How the laws of physics lie” …

      • Thanks, I been referred to Cartwright before as many people in the ‘softer’ sciences regard her as having something important to say. At the abstract begins:

        “Nancy Cartwright argues for a novel conception of the role of fundamental scientific laws in modern natural science. If we attend closely to the manner in which theoretical laws figure in the practice of science, we see that despite their great explanatory power these laws do not describe reality. Instead, fundamental laws describe highly idealized objects in models. Thus, the correct account of explanation in science is not the traditional covering law view, but the ‘simulacrum’ account. …”

        This is dated 1983. My (limited) understanding of Physics is that when I seem to be seeing a rainbow, there is actually no such thing where the rainbow appears to be, and that for Physicists ‘it is rainbows all the way down’. Maybe I am missing something? I tend to go with Whitehead/Keynes/Russell/Turing on this sort of thing, but do you think there is something I should seriously read?

        • Try Cartwright’s “The dappled world: a study of the boundaries of science” (CUP 1999)!

  2. It seems to me that this discussion exposes the nakedness of scientific theory. There is no scientific theory that has stood the test of time – for instance, Newton’s Universal Theory of Gravitation is not universal (Einstein saw to that). The Earth was once flat, now it’s round. The celestial bodies once revolved around the Earth, now the Earth is one of many bodies in complex relative motion. Statistical mechanics governs the laws of quantum mechanics and the behaviour of matter at infinitesimal scale. Underlying statistical mechanics/quantum mechanics is a theory of probability which is an intellectual construct designed to explain phenomena which are otherwise unexplainable. (I cannot pull out my probability meter and measured what the probability of rain will be today.) We have a 60 year old theory of physics which purports to be a theory of everything (String Theory) which is in search of data to either validate it or falsify it (or perhaps I should be more scientifically correct, which to my mind is no different than being politically correct, and say it is in search of data which will not falsify it). Today’s scientific law is tomorrow’s garbage disposal occupant. So where is the absolute? Where is the unchanging? The history of science is one of change – some would say this is progress – maybe – but change is the only constant. As science gropes around endeavouring to discover the ”truth”, one wonders whether science is all that it is cracked up to be and nothing more than curve fitting. Physics is ultimately no different than economics.

    • I can think of three differences:
      1. Scientists don’t pretend that their results are anything other than empirical, whereas mainstream economics resembles dogma. (IMHO)
      2. Science has standards that if adhered to would seem to ensure that their results are honest, whereas economics has no such standards.
      3. Some sciences, such as physics, generally seem to follow their avowed standards. (Others, less so.)

      What they have in common is that their products are often mis-sold. But if you can get past that then most sciences seem to have more ‘truth’ to them than most economics.

  3. Your differences amount to differences in methodology – which, by and large, seem fair enough.

    And of course, a science like physics can conduct experiments which will produce equivalent results whether done today or next decade. This is hardly likely in economics.

    But I don’t think science can escape the charge of curve fitting – not that there is inherently anything wrong with curve fitting – it provides the basis upon which engineering solutions to problems can be developed. However, it seems to me science attends to all things, but in actuality, comprehends nothing.

    What is gravity?

    What is matter?

    What is time?

    Why does free, empty space have a finite electromagnetic impedance? How can anything that is empty space have a physical property – yet science can calculate an impedance for an electromagnetic wave traveling in free space. This impedance apparently gives rise to a finite speed for light. Perhaps there is an ether – but that was yesterday’s truth and is now today’s garbage.


    ” But if you can get past that then most sciences seem to have more ‘truth’ to them than most economics.”

    Perhaps, other than today’s “truth” is more than likely to be tomorrow’s garbage. And because “truth” in economics is, more often than not, underwritten by ideology, it is more enduring and strongly held.

    • Henry, it seems to me that in his Principia Newton strives to explain his notion of ‘scientific truth’, his methodology, his results, and their limitations. In his sense, his theory is as true (subject to his caveats) as it ever was.
      In my view, genuine empirical theories should be underpinned by explicit notions of truth etc with at least the credibility of Newton’s. So the question is not the extent to which economic theories resemble scientific theories, or the extent to which they are believed, but what underpins them.

  4. “So the question is not the extent to which economic theories resemble scientific theories, or the extent to which they are believed, but what underpins them.”
    I’m not sure what you mean by underpins. Do you mean they should be empirically supported?
    Some other comments.
    Firstly, admittedly, my comments on science have been hyperbolic. I guess I have reacted to the use of the word “truth”. The word to me at least implies constancy and consistency. The history of the development of science demonstrates that this word is barely applicable to scientific theories. Additionally, while Newton’s Law of Gravitation applies consistently to physical phenomena of a certain scale (e.g. planetary scale), it fails at other scales (e.g. nuclear scale). Even the idea that the Earth is flat might be justified at a local scale. So there’s the question of scale which can obscure the consideration of “truth” – the Law is consistent at one scale and not another. And it’s not even consistent at a macro scale – the aberrations in the perihelion precession of Mercury for instance. So I think we have to be very careful throwing the word “truth” about.
    Secondly, given the nature of the phenomena that economics studies, to call economics a science in the sense that physics is a science, is problematic. Physical phenomena behave in repeatable ways – the motions of Jupiter measured today will conform to the same equations as the measurements of its motion 10 years hence. This can hardly be said for economic phenomena. I don’t believe economics can ever be scientific in the sense that physics is.
    Thirdly, this blog started with the question, “are (there) any Laws of Nature. And if so — are they really ‘facts of life”. I can’t see that we could ever answer this question with any reliability. What if the way we perceive physical phenomena is given by the evolutionary development of our brain functioning? As organisms we are optimized for survival. Our sensory apparatus and the means by which the data generated is processed is presumably geared to survival of the organism – this capacity is sufficient and perhaps only sufficient for our guaranteed survival as a species. Would an amoeba, which appears to have limited sensory apparatus, derive the same laws of nature as a human being would? If we could smell the gravitational pull of the moon, would it impact on the way we construct laws about the motion of the moon relative to the Earth?

    • Yes, I think that knowledge claims should be ‘empirically supported’ in some explicit, credible, sense, such as Newton’s. (Other notions are available.) For example, he is not claiming that his ‘laws’ are ‘true’ in the sense that you are looking for. Indeed, it would seem impossible for any empirical claims to be true in your sense. But they can be true in a sense that is much stronger (and more ‘useful’) than any sense in which mainstream economics might be said to be true, and I think this a useful distinction. Thus, for Keynes, sciences are regarded as true because we have found them ‘true enough’, whereas we have not found economics to be adequate and so are not so justified as regarding it as true.

      One ‘problem’ with scientific theories are that, like Newton’s, they tend to be corrupted by strong subjective elements, as in your final point. But they still have some ‘truth’. For example, if we try driving a car with Newton’s laws in mind we may be successful, except when our senses are corrupted by drink. We ought to recognize that even when sober our senses aren’t ‘objective’, but no-one has ever had a crash due to a failure of Newton’s laws.

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