Does science ‘prove’ its theories?
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| Charles Sanders Peirce (1839 – 1914) (Photo credit: Wikipedia) |
Dawkins often argues that there’s no need for faith in science, in that the evidence for a correct conviction compels us to accept its truth. He first set out his views on this matter in The Selfish Gene in 1976 and has not changed his mind since.
[Faith] is a state of mind that leads people to believe something—it doesn’t matter what—in the total absence of supporting evidence. If there were good supporting evidence, then faith would be superfluous, for the evidence would compel us to believe it anyway.
Though this seems clear and persuasive, it’s actually an unsustainable view of the relation of evidence and belief in the natural sciences simply because it fails to make the critical distinction between the ‘total absence of supporting evidence’ and the ‘absence of totally supporting evidence’.
For example, consider the current debate within cosmology over whether the Big Bang gave rise to a single universe or a series of universes (the so-called multiverse). There are many distinguished scientific colleagues who support the former approach, and equally distinguished scientific colleagues who support the latter. Both are real options for thinking and informed scientists, who make their decisions on the basis of their judgements of how best to interpret the evidence and who believe—but cannot prove—that their interpretation is correct. This process rather inconveniently doesn’t fit at all with Dawkins’ bold declaration that ‘if there were good supporting evidence, then faith would be superfluous, for the evidence would compel us to believe it anyway’. Dawkins himself clearly believes in the multiverse theory, but the evidence for it just isn’t good enough to compel him—or anyone else—to accept it. Science just isn’t like that.
In its rigorous sense, ‘proof’ applies only to logic and mathematics. We can prove that 2 + 2 = 4, just as we can prove that ‘the whole is greater than the part’. Nevertheless it’s important to avoid confusing ‘provability’ with ‘truth’. As we noted earlier, the great mathematician Kurt Gödel famously proved that however many rules of inference we formulate, there’ll still be some valid inferences that are not covered by them. In other words there are some statements that are true that we may not be able to show to be true. The philosophical implications of this are considerable.
In science, as we make a series of observations we’re forced to address the questions: ‘What must be true if we are to explain what is observed?’ ‘What “big picture” of reality offers the best fit?’ The American scientist and philosopher Charles S. Peirce (1839–1914) used the term ‘abduction’ to refer to the way in which scientists generate theories that might offer the best explanation of things. The method is now more often referred to as ‘inference to the best explanation’.
A classic example of this can be found in Charles Darwin’s Origin of Species (1859), now widely seen as a landmark in scientific history. New Atheist websites often assert that Darwin proved his theories, contrasting this unfavourably with the ‘blind faith’ of religion. Darwin himself knew otherwise. He believed that his theory of ‘natural selection’ provided the most elegant and persuasive explanation of biological life forms—but he knew he couldn’t prove it. The problems were obvious.
To begin with, there was no ‘smoking gun’—no knock-down, unambiguous evidence that would conclusively and incontrovertibly compel people to accept his theory. Everything that was known about the natural world could be accommodated by rival theories, such as transformism. Furthermore there were serious scientific objections and difficulties to his theory that made it unacceptable to many scientists of his day. The most significant of these was probably the problem of genetic dilution. Darwin lacked a viable theory of genetics to explain how inherited characteristics were transmitted to subsequent generations.
Yet despite some formidable difficulties, Darwin believed that his theory was right and would one day be shown to be so. How, he asked, could a theory be wrong when it made so much sense of what he observed? Yes, there were loose ends everywhere and a large number of problems. But his core idea seemed to him to be correct—even though it couldn’t be proved.
… a crowd of difficulties will have occurred to the reader. Some of them are so grave that to this day I can never reflect on them without being staggered; but, to the best of my judgment, the greater number are only apparent, and those that are real are not, I think, fatal to my theory.
So does science prove its theories? There are certainly some things that science (as opposed to logic and mathematics) can prove and has proved—that the chemical formula for water is H2O, for example, or that the average distance of the moon from the earth is about 384,500 km. But these are basically facts about our world. The big scientific questions concern notions about the origins of the universe, the nature of force and matter and perhaps the biggest question of all: is there a Grand Unified Theory that can explain everything? We can give to these questions good answers that we believe can be justified from the best evidence at our disposal. But we can’t give a final answer because we know that what scientists believe today may not be what scientists believe in the future. No wonder standard scientific textbooks rightly emphasize that ‘science rests on faith’.
Most people don’t have a problem with this. Faith is just part of human life and plays an important role in science as it does everywhere else. However, the New Atheism tends to have an aversion to the word, believing that ‘faith’ denotes some kind of intellectual perversity reserved for deluded religious fools. Faith, we’re told, is invariably blind faith. Quite clearly it’s not: belief is just a normal human way of making sense of a complex world. As the philosopher Julia Kristeva observed: ‘Whether I belong to a religion, whether I be agnostic or atheist, when I say “I believe,” I mean “I hold as true.”
In the end, science is about giving us reasons for believing that certain things are true, while at the same time insisting that we realize that future generations may rightly want to challenge these beliefs. That’s why science is so successful: it’s willing to change its mind in response to new evidence. But what about things that lie beyond the scientific method?
McGrath, A. (2011). Why God Won’t Go Away: Engaging with the New Atheism (pp. 74–77). London: SPCK.
