How do I know what I know?

A great post from Nick Hornby on the subject of global warming:

I’m pretty sure, for example, that global warming is happening, and that we are in serious trouble; but if one of those cranky people who deny it all sat me down and started shouting at me, I would have very little to come back at him with, if it got down to facts and figures. Climate-change sceptics, for example, believe that ice-cores indicate a pattern of temperature and CO2 increases every one hundred thousand years or so, but that C02 levels have always gone up after the temperature rise, not before. Is that right? I don’t know – how could I? How could any of us who are not climate scientists? Nor do I know whether it’s helpful, or indeed what it might prove, for that matter. Most scientists, as far as I can work out, seem to believe that it’s true but irrelevant. I am a father, an adult, a writer, so I should have a view, right? But I have an ‘O’-level in biology.

This raises an issue that has long plagued me since I began this blog, namely: how little of what I know to be true is actually provable. Once you've given ground to the idea that some scientists might be wrong, or that some history books might be biased, or that the news misquotes people, it's amazing how little you are left holding. The sun rises in the East, love is all that matters, and WALL-E is the best film I've seen all year: that's about it for me.

The rest of the stuff in my head is all on loan from others, much of it on trust and some of it gathering dust. So-and-so turned out to be reputable on that subject, this book didn't let me down there, that guy sounds like he's lying.....

Actually that last is probably the most effective way of getting at the truth. So with climate change for instance, it's easier to disbelieve the skeptics, because I can discern clear motive as to why they might want it so (the consequences are costly, its bothersome, why oh why must I care about ice caps, etc etc). The people promoting climate change, however, have very little incentive to make up a scary scientific theory promising imminent global doom. It's as much of a pain in their behinds as it is in everyone else's.

It's Occam's Razor: the simplest theory wins. I can't personally prove the holocaust happened. But the theory required to explain why, if it didn't happen, everyone appears to believe it did, would be so massive and complicated and backed-up on itself — each explanation requiring its own counter-explanation — that you would wake up every morning feeling like Oliver Stone. Maybe that's what many of my beliefs come down. I just don't want to wake up feeling like Oliver Stone every morning.