Lynsey asked:

Debates between evolutionary biologists and ‘scientific creationists’ have been famously unproductive, with each side employing distinct criteria of judgment. Can the philosophy of science proposed by Karl Popper resolve the impasse for objective rational bystanders, and if so, how?

Answer by Craig Skinner

The short answer is NO. Popper formulated his view more than 70 years ago, the debates and impasse continue.

A longer answer is necessary.

Popper was impressed by the difference between psychoanalysis and Marxism on the one hand, and Einstein’s General Theory of Relativity on the other. Whereas the former systems could accommodate any observations, the latter made surprizing predictions which, if not observed, would refute the theory. So, for example, Adler’s psychoanalysis specified the early experiences allegedly causing an inferiority complex. This ‘explained’ why a person who lacked confidence and let people walk all over him had his inferiority complex. But suppose a person with the same early experiences was confident and forceful – didn’t this refute the theory? No, he had an inferiority complex ‘really’, and his opposite traits were a reaction to this. And so on. The theories could never be refuted.

Einstein, contrariwise, predicted bending of starlight near the sun, differing from what Newton predicted. If Einstein’s prediction was wrong, his theory would be refuted. Famously, he was right. Popper proposed falsifiability as the key criterion for distinguishing science from pseudoscience. It proved a popular suggestion, especially with scientists, who were presented as heroic figures willing to let their cherished theory die at the hands of a single awkward fact, which is not how scientists actually work.

To turn to creation science now, and resolving the ‘impasse’.

There are 2 distinct issues:

1. Is ‘creation science’ (or its modern version ‘intelligent design’) science or religion?

2. Which explanation for biodiversity does the evidence favour – evolution or special creation?

1. Is it science?

This has been the subject of heated US debate. The reason? The US constitution forbids the teaching in schools of any particular religious views as being established. So if creationism is religion it cant be taught, whereas if it’s science it can. If creationists can get their view accepted as science, they win the battle. The constitution allows bad, as well as good, science to be taught, so creationism could be given equal time with evolution. So far the courts have ruled that creationism is religion. They have had to specify the criteria distinguishing science from pseudoscience, and have suggested (i) Explanation by natural law (as opposed to supernatural) (ii) Views held provisionally (alterable by new evidence) (iii) Testability against the empirical world (iv) Falsifiability (able to suggest observations/ experiments which could refute the theory)

Creationists counter that (i) begs the question, that they do hold views provisionally, that their views are testable and falsifiable e.g. that the Earth is 6000 years’, not billions of years’, old; that human ancestry is entirely separate from apes. They have a fair point and maybe evolutionists should accept that creationism is bad science, and let people decide on the evidence.

2. Which explanation does the evidence favour?

I think the evidence in favour of evolution is overwhelming for ‘objective rational bystanders’. But, on the whole, that’s not what people are, especially in the US. Popper’s falsifiability criterion plays its part (countless observations, any of which could have refuted evolutionary theory, have been made).

But science is not in the business of proof. That’s for logic and maths, and doesn’t tell us anything about the world. Science is about giving the most likely explanation for what we observe, given current evidence. Strictly, no theory can be falsified: faced with a contrary finding, rather than giving up the theory we can give up an auxiliary hypothesis eg the observations are wrong, the instruments were faulty etc. And, strictly, no theory can ever be 100% confirmed: for any set of observations, there is always more than one explanation consistent with them – indeed an infinity of explanations. So, no amount of evidence can disprove a hypothesis (Duhem’s problem), no amount of evidence can prove a hypothesis (Hume’s problem), simply emphasizing that science is not in the proof business.

Others, such as Kuhn, Lakatos and Thagard, have proposed alternative demarcation criteria. But the bottom line is that there cannot be a sharp distinction between science and pseudoscience. Judgment and familiarity with how science and scientists work are needed, This is often lacking in US citizens including most current candidates running for Presidential nomination. The latter include creationists, and ‘global warning fears are a conspiracy’ merchants, but nobody with a background in science or philosophy.