There’s a certain beauty in truth. It has simplicity, defensibility.

It’s beautiful because it’s simple. It’s beautiful because it comes with no excuses, and there are none you have to make for believing it, none you have to make for saying it. You don’t have to come up with labyrinthine apologetics and expedient political justifications for believing something or arguing for something when there’s a wealth of cold, clear evidence that indicates you should. When you can pull a fossil out of a drawer, pull sequences out of the search engines, point out the slow, steady trickle of changes in noncoding regions, sit your back against the lines in the rock carved by millennia of water, hike into the Gatineau hills, stand on billion-year old gneiss and granite, when you can do all that, there’s nothing much more you should have to say.

Touch that stone, for that matter, if you will. Press the palm of your hand against it. It’s cool, a little damp, in the cool, damp air of the late fall.

It’s been there a billion years—or a little more—and you can draw isochron graphs that illustrate how you know this. The lines are straight, unequivocal. They point like an arrow at a number. A rather large number.

When I say there is beauty in truth, I’m not saying there’s anything necessarily beautiful about what is true. This is worth clarifying because this is a frequent source of confusion. Much about what you discover to be true may be upsetting to preconceptions you once entertained. Much about what you discover to be true may be upsetting merely because you wish it were not so, for reasons that may either be obvious or entirely obscure to yourself. And sometimes, the real world can simply be ugly. Knowing what is true doesn’t always make you entirely happy.

But I contend the truth is still beautiful, in a very fundamental way, for those essential reasons, given above. Simplicity, defensibility. Strip away what you wish were so, strip away what you suspect your audience may wish to hear, strip away the softening qualifications you might be tempted to slip into the way you describe it, to avoid upsetting those you fear aren’t ready to hear it, and there it is: the cool, serene, unapologetic centre of existence. It’s like that ancient stone. Everything is built on it.

There is a minor paradox, here. Part of the truth is uncertainty. The ultimate truth is we live with a little doubt, and always will. There are error bars on the number those isochrons point at—though these are small, against the scale of that number. Has it been 1.2 billion years, since last this stone was molten? Or is it 1.19? And like that number, everything we think we know, we must say we know with qualifications. That cold, hard stone is still very obviously down there, but what we know of it is subject to revision, now and then. And there is always a little more to learn.

We know beyond all reasonable doubt we and the chimpanzee had a common ancestor—but exactly when, this too is a number, and there is noise in the results. When? Exactly when?

Well, we can’t quite say. Not yet. And whether we’ll ever be able to do so to your satisfaction may depend on how precisely you wish to know.

And that phrase above, there—beyond all reasonable doubt—that phrase is a necessary part of every honest human being’s world. It’s not a hedge; it’s just the truth, again, and the best we can do to describe it.

And sometimes, we make interesting mistakes, find parts of what we think we know, we may have got very wrong, in some odd way or another. There are always questions. Is it three kingdoms or two?

Yet still, error bars and uncertainty aside, we know so often what is most likely. We frequently can touch that stone, well enough, when we’re simply honest with ourselves, when we try hard enough to be

And, at the very least, when we’re honest with ourselves, we can very frequently be quite certain about what isn’t true.

In fact, that’s generally a lot easier.

I started this very elliptical discussion with a statement about beauty, and I did that because, to me, that’s ultimately what so much of this is about. It is very much a matter of aesthetics, of preference, of taste.

That beauty in the simplicity of truth, that, for me, is what the fight is really about, in this recent flare-up at the Panda’s Thumb, at Pharyngula, and at Dr. Moran’s new blog. And for me, again, it is an aesthetic thing:

The truth of the science is simple, beautiful. It needs no excuses.

And none should be made, therefore, on its behalf.

So when someone comes to you with hazy notions of a divine mind somehow directing biological evolution, you have no stone, no fossil, no sequence, no graph that says this is so. You cannot place your hand on that.

Almost certainly, you can’t because there’s nothing there to place your hand on, and never has been. What certain people wish to believe notwithstanding. But never mind. Even that rather reasonable assumption is perhaps less central than the more immediate issue. Which is, again: you have no reason to say it is so.

So what are you to say, then? Are you to smile indulgently, and let the waters be that little bit muddied, in that possibly inconsequential way? Are you to say in response, well, that could be true…

I’d say no.

Again: you have absolutely no reason to say it is, nothing to stand on, nothing to touch, there, and you know that perfectly well. So you’re violating a very simple, very fundamental and very important principle in allowing it to stand…

You’re complicating a simple truth with a hazy, lazy half-lie. The half-lie being that there’s any place for that supposition in a simply honest discussion that started from what we had evidence for, and which should have ended there.

And it has to end there, by my lights. This is how we respect the beauty of simple truths.

If you respect that beauty, what you have to say when people come to you with such hazy, wishful notions is simply, again, what is true: we have absolutely no reason even to entertain that particular speculation. The notion of such divine minds is an old human belief, but we have never found anything material that supports it. Biological evolution, so far as anyone has ever determined, has no mind behind it, and it’s very difficult to imagine how it possibly could have. Just a teeming sea of blindly replicating genes, and they go where chance and their environment will let them.

This is reasonable for the relatively subtle equivocations of ‘theistic evolution’. As for the far wilder claims and outright fraud that are also sometimes brought to the table—the stuff the creationists bring—even putting it as gently as ‘we have no such evidence’, in such cases, is rather being too kind.

As I said above: we very frequently know very well what isn’t true.

So there is no reason not to say so.

So in the matter of Moran and Myers (and Dawkins and the rest of the much-maligned ‘evangelical atheists’ accused of picking fights they apparently don’t need) versus their detractors at the Thumb, I really have to say this:

My aesthetic sense and the principles they guide find for Moran et al.

They didn’t start this fight. Or rather, if they did, they did it only doing what they should: keeping to honesty, keeping to simplicity. That a howling horde of angry fundamentalists and a slightly quieter legion of unsettled mainstream believers in old tribal deities apparently don’t like it much, this changes nothing.

The first duty still has to be to simple truths and their beauty.

That is all.