In RE: scientific certainty

I got a message from reader DC about the last post, reminding me that scientists understand that their theories are always provisional. I think functionally that isn't really true, as I wrote in an email to him:

I would say that there is a real problem about "certainty" in our culture. I think it's just the human condition at this time. We are a quite fearful race, though I suppose it's not so long ago that we shuddered in trees hiding from predators. Science, as we receive it in popular media, is presented as certain knowledge. You see how even scientists themselves can fall prey to that in the discovery that there are different kinds of DNA in different cells in our bodies. This was an idea that apparently didn't occur to anyone for years, because (I would argue) the "truth" that every person's DNA was absolutely unique went unquestioned. Now I wonder if they will discover that DNA from certain places can be very similar, or even shared among humans, and what that would do to the forensic use of DNA evidence, and criminal cases going back decades.. it boggles the mind. Hopefully it won't come to that, but you see how this idea of scientific certainty has left us vulnerable to such surprises.

I think individual scientists may well keep in mind that their theories are always provisional, but as a culture, we've been treating them as immutable laws, and it's easy to pick out areas where this feeds right back into science. The idea that mankind came to the Americas only 12,000 years ago springs to mind.. The evidence that this was in error was ignored for decades because of that "certainty". This is what I'm talking about.

Thanks to reader DC for the thought provoking email.