His arguments are still relevant and we can take inspiration from them to reply to the current claims that philosophy is useless to physics. Today, after a couple of millennia during which both philosophy and science have developed considerably, historical evidence regarding the influence of philosophy on science is overwhelming. Here are a few examples of this influence, from astronomy and physics. Ancient astronomy — that is, everything we know about the Earth being round, its size, the size of the moon and the sun, the distances to the moon and the sun, the motion of the planets in the sky and the basis from which modern astronomy and modern physics have emerged — is a direct descendent of philosophy.
The questions that motivated these developments were posed in the Academy and the Lyceum, motivated by theoretical, rather than practical concerns. Centuries later, Galileo and Newton took great steps ahead but they relied heavily on what had come before. Galileo's work would have been inconceivable without Aristotelian physics. Newton was explicit about his debt to ancient philosophy, Democritus in particular, for ideas that arose originally from philosophical motivations, such as the notions of empty space, atomism and natural rectilinear motion.
His crucial discussion about the nature of space and time built upon his discussions with and against Descartes. In the 20th century, both major advances in physics were strongly influenced by philosophy.
A typical week
The philosophical influences on the conception of general relativity were even stronger. Once again, he was explicit in recognizing his debt to the philosophical arguments in Leibniz, Berkeley and Mach. Einstein claimed that even Schopenhauer had had a pervasive influence on him. Why this influence? Because philosophy provides methods leading to novel perspectives and critical thinking.
Philosophers have tools and skills that physics needs, but do not belong to the physicists training: conceptual analysis, attention to ambiguity, accuracy of expression, the ability to detect gaps in standard arguments, to devise radically new perspectives, to spot conceptual weak points, and to seek out alternative conceptual explanations. This independence created by philosophical insight is—in my opinion—the mark of distinction between a mere artisan or specialist and a real seeker after truth. Here is a second argument due to Aristotle: Those who deny the utility of philosophy, are doing philosophy.
The point is less trivial than it may sound at first. Weinberg and Hawking have obtained important scientific results. In doing this, they were doing science. They were reflecting on the best way to develop science. The issue is the methodology of science: a central concern in the philosophy of science is to ask how science is done and how it could be done to be more effective.
Good scientists reflect on their own methodology, and it is appropriate that Weinberg and Hawking have done so too. But how? They express a certain idea about the methodology of science. Is this the eternal truth about how science has always worked and should work?
Physics Needs Philosophy / Philosophy Needs Physics
Is it the best understanding of science we have at present? It is neither. In fact, it is not difficult to trace the origins of their ideas. They arise from the background of logical positivism, corrected by Popper and Kuhn. The current dominant methodological ideology in theoretical physics relies on their notions of falsifiability and scientific revolution , which are popular among theoretical physicists; they are often referred to, and are used to orient research and evaluate scientific work. The imprint is unmistakable. Thus, when Weinberg and Hawking state that philosophy is useless, they are actually stating their adhesion to a particular philosophy of science.
In principle, there's nothing wrong with that; but the problem is that it is not a very good philosophy of science. On the one hand, Newton, Maxwell, Boltzmann, Darwin, Lavoisier and so many other major scientists worked within a different methodological perspective, and did pretty good science as well. On the other hand, philosophy of science has advanced since Carnap, Popper and Kuhn, recognizing that the way science effectively works is richer and more subtle than the way it was portrayed in the analysis of these thinkers.
The weakness of their position is the lack of awareness of its frail historical contingency. They present science as a discipline with an obvious and uncontroversial methodology, as if this had been the same from Bacon to the detection of gravitational waves, or as if it was completely obvious what we should be doing and how we should be doing it when we do science. Reality is different.
Science has repeatedly redefined its own understanding of itself, along with its goals, its methods, and its tools. This flexibility has played a major role in its success. Let us consider a few examples from physics and astronomy. Contrary to expectations, it turned out that Earth was itself one of the heavenly bodies.
After Copernicus, the goal appeared to be to find the right combination of moving spheres that would reproduce the motion of the planets around the Sun. Contrary to expectations, it turned out that abstract elliptical trajectories were better than spheres.
Physics and Philosophy Specialist (Science Program) - ASSPE2584
After Newton, it seemed clear that the aim of physics was to find the forces acting on bodies. Contrary to this, it turned out that the world could be better described by dynamical fields rather than bodies.
After Faraday and Maxwell, it was clear that physics had to find laws of motion in space, as time passes. Contrary to assumptions, it turned out that space and time are themselves dynamical. After Einstein, it became clear that physics must only search for the deterministic laws of Nature. But it turned out that we can at best give probabilistic laws. And so on. Here are some sliding definitions for what scientists have thought science to be: deduction of general laws from observed phenomena, finding out the ultimate constituents of Nature, accounting for regularities in empirical observations, finding provisional conceptual schemes for making sense of the world.
The last one is the one I like. Science is not a project with a methodology written in stone, or a fixed conceptual structure. It is our ever-evolving endeavor to better understand the world. In the course of its development, it has repeatedly violated its own rules and its own stated methodological assumptions. A currently common description of what scientists do is collecting data and making sense of them in the form of theories.
As time goes by, new data are acquired and theories evolve. In this picture scientists are depicted as rational beings who play this game using their intelligence, a specific language, and a well-established cultural and conceptual structure. The problem with this picture is that conceptual structures evolve as well. Science is not simply an increasing body of empirical information and a sequence of changing theories. It is also the evolution of our own conceptual structure.
It is the continuous search for the best conceptual structure for grasping the world, at a given level of knowledge. The modification of the conceptual structure needs to be achieved from within our own thinking, rather as a sailor must rebuild his own boat while sailing, to use the beautiful simile of Otto Neurath so often quoted by Quine. This intertwining of learning and conceptual change and this evolution of methodology and objectives have developed historically in a constant dialogue between practical science and philosophical reflection.
The views of scientists, whether they like it or not, are impregnated by philosophy. And here we come back to Aristotle: Philosophy provides guidance how research must be done. Not because philosophy can offer a final word about the right methodology of science contrary to the philosophical stance of Weinberg and Hawking. But because the scientists who deny the role of philosophy in the advancement of science are those who think they have already found the final methodology, they have already exhausted and answered all methodological questions.
Three Recent Books On Physics And Philosophy
They are consequently less open to the conceptual flexibility needed to go ahead. They are the ones trapped in the ideology of their time. One reason for the relative sterility of theoretical physics over the last few decades may well be precisely that the wrong philosophy of science is held dear today by many physicists. Popper and Kuhn, popular among theoretical physicists, have shed light on important aspects of the way good science works, but their picture of science is incomplete and I suspect that, taken prescriptively and uncritically, their insights have ended up misleading research.
The combination of the two has given rise to disastrous methodological confusion: the idea that past knowledge is irrelevant when searching for new theories, that all unproven ideas are equally interesting and all unmeasured effects are equally likely to occur, and that the work of a theoretician consists in pulling arbitrary possibilities out of the blue and developing them, since anything that has not yet been falsified might in fact be right. I think that this methodological philosophy has given rise to much useless theoretical work in physics and many useless experimental investments.
Arbitrary jumps in the unbounded space of possibilities have never been an effective way to do science.
The reason is twofold: first, there are too many possibilities, and the probability of stumbling on a good one by pure chance is negligible; more importantly, nature always surprises us and we, limited critters, are far less creative and imaginative than we may think. The radical conceptual shifts and the most unconventional ideas that have actually worked have indeed been always historically motivated, almost forced, either by the overwhelming weight of new data, or by a well-informed analysis of the internal contradictions within existing, successful theories.
Science works through continuity, not discontinuity. He was using ellipses as an approximation for the deferent-epicycle motion of Mars and was astonished to find that the approximation worked better than his model. In both instances, the important new idea was forced by data.