I Love Science

Science starts with observation. We look at the world, and we notice things. Many of these things seem to be related, and so we try to come up with an explanation as to how they’re related. This explanation is called a Theory… we can think of these as ‘Big T’ Theories, because they are based on demonstrable evidence and they have wide explanatory power. Scientists then test the Theory in order to prove that it is wrong. This is an important point, and it seems to constantly confuse non-scientists. Science doesn’t try to prove that a Theory is correct. Science tries to prove that the Theory is [i]wrong[/i], and the Theory is accepted only so long as we are unable to show that it is wrong.


Contrast this with our everyday ‘theories’ (my neighbour is probably cheating on her taxes… my friend is having an affair), which are simply vague hunches or convenient fictions - we can think of those as small-t theories. Usually we go looking for evidence to support these ‘theories’, and it is common for us to ignore evidence that contradicts them. It seems to me that it's these vague hunches or convenient fictions that people have in mind when they say that evolution is ‘just a theory’.


Some people claim that the Theory of Evolution is not a real theory because ‘it cannot be falsified’. This is a nonsense. So, what would falsify the Theory of Evolution? Well, if we opened up a stratum of the Earth’s crust that was laid down, say, 100 million years ago and found there the fossilised remains of a modern-day giraffe, then the Theory of Evolution would have a fatal problem. The same would apply if we found fossils out of place in the Earth’s strata. Every single fossil puts the Theory of Evolution at risk, and yet, despite the hundreds of millions of fossils on the record, the Theory still stands. We never see a ‘modern’ rabbit (as an example) suddenly appearing in fossils formed, say, 60 million years ago. The Theory of Evolution is drawn from the evidence… and the evidence we continue to gather consistently fails to falsify it... but we continue to look.


Testing the evidence from which a Theory is developed is complemented by testing the consistency and coherence of the Theory itself (if our Theory is valid, then we should see the following…). This is where science uses the (much-misunderstood) hypothesis.


At its heart, a hypothesis says things like: “because of the evidence we have, the Theory says that chimps and humans have a common ancestor. It therefore follows that there will be strong genetic matches between chimps and humans”. Then we examine the genes of both.


It’s worth noting that even at this level we aren’t trying to prove that the hypothesis is correct… we try to show that it’s [i]incorrect[/i]. To achieve this, we form a Null Hypothesis, which in this case might be “there are no more similarities between chimps and humans than between any other two species”… and we then try to show that to be the case. This is an important point. We don't try to show that the hypothesis is valid... we try to show that the null hypothesis is valid.


If we cannot show that the Null Hypothesis is correct (i.e. we find that there are, in fact, enormous similarities), then we still don’t say that the hypothesis is correct… we say that we have ‘failed to accept the null hypothesis’. After all, we may have made an error, or missed something, and the next person to test the hypothesis might find reason to accept the null hypothesis.


So science doesn’t try to ‘prove’ its theories are correct, nor does it try to ‘prove’ that the hypotheses that come from those theories are correct. Science collects evidence in an attempt to disprove the theories it has formed from earlier evidence, and tests the validity of those theories by forming and testing hypotheses that would invalidate them.