23 But How Do We Know the Laws of Nature Are True?

As we have seen, if alleged knowledge should count as genuine knowledge only when we have the sort of absolute certainty that would shock a skeptic into amazed silence, then we do not have genuine scientific knowledge. But in that case, we have hardly any genuine knowledge whatsoever, and we have seen where that leaves us. So suppose we lower our standards a bit so as to allow many of the items we typically regard ourselves to genuinely know: that we have hands, that our senses typically do not deceive us, that regular and constant patterns in our experience (like apples falling and clothes drying and water freezing) will continue to hold in the future, that other people exist, and so on. Suppose, in short, we adopt a more ordinary attitude toward our experience. Given our ordinary attitude toward our experience, the one we have when an extreme skeptic is not pestering us, do we have good reason for counting our alleged scientific knowledge as genuine knowledge?

It might seem that the answer is obviously yes. After all, every scientific claim is accompanied by a list of observations and experiments that (in principle) anyone can access or perform. These observations and experiments belong in the sphere of our ordinary knowledge of the world. The scientific claims or theories are based upon those observations and experiments through the general method outlined in accounts of “the scientific method.” This makes scientific knowledge continuous with our ordinary knowledge of the world and just as genuinely known. The idea here is that we can take any reasonable person who trusts their experience and show them step-by-step how we have reached the scientific conclusions we have reached and why these conclusions are reasonable to believe even if, as we admit, there is always the possibility that we might be wrong about some or all of it.

But here is a line of objection that might be presented. The central idea is one articulated by Thomas S. Kuhn (1922-1996), though it should be pointed out that Kuhn himself never used this idea to criticize scientific knowledge. Still, others influenced by Kuhn have used the idea to this end. The idea is this: scientists are always coming up with the best theories they can given the ideas they have, the evidence at the time, and what they are interested in. When scientists come up with these theories, they are creating a paradigm or a worldview that basically says “here are the problems we are interested in, and here are the methods we should use to solve them.” Then teams of scientists normally get to work trying to solve the problems they are interested in. We can call this period of normal scientific activity normal science.

Every so often some scientist develops a new paradigm or worldview that is radically different from the one being employed in normal science. The paradigm presents a wholly different view of the world, a different set of problems to solve and a different set of methods to use in solving them. Sometimes these new paradigms just fail—no one else gets interested in them, they don’t work very well, and they sputter and die. But sometimes younger scientists get very excited by the new paradigm. They regard it as an exciting and useful new development, and they begin to use it and promote it to others. Over time the new paradigm may take the place of the old paradigm, and that is when a paradigm shift or a scientific revolution occurs.

What causes a paradigm shift to occur? What explains the success of a new paradigm? For a long time historians of science believed that a new paradigm is successful when it allows for better predictions or better methods of solving problems. But Kuhn’s work in the history of science showed that this is not so, or at least, not always so. Remember, the new paradigm is radically different from the old paradigm. This means that the standards of what counts as “better predictions” or “better methods” also changes. There is no common standard of measure between an old paradigm and a new paradigm. For this reason, Kuhn called paradigms incommensurable: there is no meaningful way to compare one to the other.

So a paradigm shift does not happen because the new paradigm is clearly better than the old one. Rather, Kuhn argued, a paradigm shift happens because purely human and historical conditions give the new paradigm an advantage over the old one. In the simplest possible case, the old guys defending the old paradigm eventually die, and the younger guys with the new paradigm get their jobs causing the paradigm shift to occur. In more realistic and complicated cases, there are political and economic and ideological pressures that all come into play and end up favoring the new paradigm over the old one. But these pressures do not guarantee that a new paradigm will be “better” in terms of being better knowledge of the world.

The end result of this—though again, not one that Kuhn himself embraced but one embraced by scholars influenced by him—is that scientific progress is an illusion. There are changes in scientific theories, of course, but the changes are not brought on by objective measurements and experiments. They are brought on by social pressures. Science, then, is sort of like fashion or the evolution of styles in art. Attitudes and styles change, and people with the new styles and attitudes view them as improvements, but really the change does not indicate that the new attitudes and styles are closer to the truth.

Objection: This could not possibly be true. After all, do we not have better medicine, better technology, and more thorough explanations of nature than any previous generation? Read again the first two paragraphs of this essay!

But here is a reply: perhaps the advances in medicine and technology would have happened anyway under the terms of the old paradigms, and the new paradigms really had nothing to do with those advances. And so far as “more thorough explanations” go, that judgment is being made from the perspective of the new paradigm. The judgment is biased toward the new view. The old paradigms also had very thorough explanations, though, of course, using different terms and ideas. What reason do we really have for believing our paradigm is better than theirs?

This last question should be taken seriously, and not just rhetorically. Are our modern scientific theories better than previous scientific theories? Could previous theories, in principle, make sense of the technological advances that have accompanied modern theories? Rather than simply concluding “well who knows? Maybe!” from the comfort of our armchairs, we might actually try to determine whether, for example, Aristotelian science could allow us to make sense of gene therapy. What new advances would have to be made by succeeding generations of Aristotelian scientists? What further elaborations would have to be made to their theories? In the end, would the revised Aristotelian theories be fundamentally different from our modern theories? Or would they just be the same idea in different words? Can someone come up with distinct neo-Aristotelian alternatives to the many ways we understand the natural world around us without simply repackaging what we think is true in Aristotelian-sounding language?

To date no one has really taken up this challenge in a thorough-going way. Of course, we can never know what twists and turns alternative histories might have made, and there is always the possibility that inventive Aristotelians could have kept their tradition going and perhaps could have led to even more impressive technological achievements. But one might well ask what evidence we have for believing this possibility is real and whether it is stronger than the evidence we have for believing contemporary scientific knowledge to be genuine. It is not enough merely to claim that a rival paradigm might have enjoyed equal success in controlling and predicting the natural world; one must show that it is true. Until that challenge has been met, we do not have good reason to think that the old paradigms are “just as true” as the newer ones.