Science cannot tell us whether or not science explains everything
Technology cannot keep pace with theoretical predictions about subatomic reality coming from physics. The same applies to our ability to observe the far reaches of the universe. Theory outstrips data and can become more extravagant with the claims it makes about the character of a reality. Theories are more underdetermined by empirical results than ever, but scientists are reluctant to admit that the arguments they put forward are philosophical and metaphysical. Their theories provide a framework in which they can operate, but if they are removed not only from actual observation but from what in principle can be accessible to us, our descendants, or even any possible observer in our universe, it is hard to see that they are anything other than the product of pure reason. Just because scientists use such reasoning does not make it science.

What then has to be the case for genuine science as such to be possible? This is a question from outside science and is, by definition, a philosophical—even a metaphysical—question. Those who say that science can answer all questions are themselves standing outside science to make that claim. That is why naturalism—the modern version of materialism, seeing reality as defined by what is within reach of the sciences—becomes a metaphysical theory when it strays beyond methodology to talk of what can exist. Denying metaphysics and upholding materialism must itself be a move within metaphysics. It involves standing outside the practice of science and talking of its scope. The assertion that science can explain everything can never come from within science. It is always a statement about science.


                      None of us can stand outside all human understanding
                  and conceptual schemes and talk of what there is or could be.

Similarly, in philosophy the question must be pressed as to where the verificationist—who believes that a proposition is meaningful only if it can be proved true or false—stands in order to deny the possibility of metaphysics. The dilemma can sometimes be expressed by the perennial challenge as to how the verification theory thesis can itself be verified. By its own lights it appears suspiciously metaphysical in that checking it through scientific means clearly begs every question. One answer is that the verification principle is an “axiom.” That, though, does not settle the question of why we should choose such an axiom. It seems somewhat arbitrary and leaves open the possibility that others can just choose a different starting place without fear of rational criticism. Nothing has then been solved.

Some philosophers, particularly of a pragmatist persuasion, have talked of the impossibility of a “God’s eye view.” None of us can stand outside all human understanding and conceptual schemes and talk of what there is or could be. We are all anchored where we are. This is a truism, but it can quickly result in questioning the possibility of any detached reasoning. It takes us very quickly to a philosophical relativism as a destination, according to which we are the creatures of time and place. That though does not just demolish the possibility of philosophy and metaphysics. It undermines the whole self-understanding of empirical science. The latter depends on the idea of a disinterested, objective reason that can be shared by all humans everywhere. It is above all concerned with truth, in effect the ultimate value guiding the practice of science that must be respected by all scientists. That is why falsifying or exaggerating the results of experiments strikes at the heart of science. Scientific truth is not respectful of persons or cultures, and it is certainly not dependent on any.

Science has a universal reach. A scientific discovery about the character of the universe should be one that notional scientists in far-off galaxies could share. The physical laws at least of our own universe remain constant and are intelligible anywhere in it. This gives a clue to a basic fact about science that is often taken for granted by working scientists. Science investigates an objective reality open to all and independent of mind.
Mathematics, though, could be claimed to be merely a tool created by the human mind. Why, then, should we assume that it can express in compressible form the workings of physical reality? Those, like Max Tegmark, who assume that the nature of reality is mathematical are making a jump between symbols that seem to be the creation of mind and a reality that not only exists independently of our knowledge of it but also far outstrips any possible knowledge. Tegmark explains the utility of mathematics for describing the physical world as “a natural consequence of the fact that the latter is a mathematical structure, and we’re simply uncovering this bit by bit.” However, this is itself a metaphysical statement about the nature of reality, logically preceding the conduct of physics.

There is much philosophical work to be done before wide-ranging statements about the character of reality can be made. Jim Baggott, writing about science, makes claims that would seem banal to many scientists. Starting with the observation that “reality is a metaphysical concept, and as such beyond the reach of science,” he points out that “scientific realists assume that reality (and its entities) exist objectively and independently of perception or measurement.” He further holds that “reality is rational, predictable and accessible to human reason.” These descriptions can be—and have been—challenged, but the assumptions are crucial to enable science to be practiced.

Reality gives science a goal and a purpose. Taking part in the practice of science without any idea of a truth that sometimes lies beyond our grasp is like playing soccer without having any goal to aim at. The game will become pointless, and so will science. Science has to be in the business of discovery. Just because reality includes human beings, it is not centered on them any more than the earth is the center of the universe. It often transcends both actual and possible human knowledge.

                             Even the greatest scientists have seen
                     that the intelligibility of the world is a mystery.

The logical independence of physical reality from mind and understanding gives science its point. The problem, as philosophers over the centuries have pointed out, is that this can open wide the gate to skepticism. If we are embedded in a reality that can be beyond our reach, how can we hope to achieve any knowledge at all? Perhaps Kant was right, and what we think we know may simply reflect the categories of the human mind. We can perhaps only deal with things as they appear to us. How things are in themselves may forever be beyond our grasp. Alternatively, the reality that we seek to understand may not even be subject to rational understanding. It may be sufficiently chaotic and disordered to be unintelligible. If we are told that this is impossible because science works, we are back with a pragmatic justification rather than a metaphysical one. It may appear convincing, but it is no defense to the worry that we could live in an accidental bay of order on the periphery of a great ocean of disorder.

How can we in science generalize from here to there, when “there” may be far beyond our reach, or from now to then, where the origins of the universe, or the far-distant future, may pose a similar challenge? This is the venerable philosophical problem of induction. David Hume, as an empiricist philosopher in the 18th century, tried to remove the need for metaphysics by saying that our reasoning concerning the uniformity of nature is not grounded in the character of reality. “It is,” he says, “not reason, which is the guide of life, but custom.”We merely expect the future to resemble the past, for example. Such a stance, which recognizes the limitations of what can be proved from human experience, can lead to profound skepticism. It can give no rational grounding to science at all. Science becomes more the expression of human nature and our preference for the familiar than a quest for knowledge. We describe what happens and give up looking for any deeper explanation as to why it does.

There is such a thing as scientific progress, and it happens through systematic trial and error or, in Karl Popper’s terminology, conjecture and refutation. A “scientific realist” has to be wary, though, about how such realism is defined. A realism that makes reality what contemporary science says it is links reality logically to the human minds of the present day. Science is then just a human product, rooted in time and place. Bringing in future science—or ideal science—may sound more plausible, but even then there is a distinction between science reflecting (or corresponding to) the nature of reality and it being simply a human construction.
Once the logical independence of reality from science is accepted, the question is why reality has a character that enables it to be understood scientifically. The intelligibility and intrinsic rationality of reality cannot be taken for granted. Even the greatest scientists, such as Einstein, have seen that the intelligibility of the world is a mystery. He famously remarked that “the eternally incomprehensible thing about the world is its comprehensibility.”Like the way in which mathematics seems to map the intrinsic rational structure of the physical world, this is presupposed within science and cannot be given a scientific explanation. It appears to be a metaphysical fact, and the explanation for which, if there can be one, must come from beyond science.
Roger Trigg is the professor emeritus of philosophy at the University of Warwick, and currently the senior research fellow at the Ian Ramsey Centre, University of Oxford. He is a former president of the Mind Association, and was the founding president of the British Philosophical Association.