Is it wrong to kill a spider you could just as easily carry outside?

The short answer The spider can’t matter enough to be the real question; you could squash it or save it and the world goes on the same. What matters is which you reach for when nothing makes you—when the thing in front of you is entirely in your power and can neither resist you nor tell anyone what you did. That’s the one moral test that never changes and never has a witness, and how you meet it in the small, unwatched cases is a truer account of you than anything you’d say about yourself. Not because the spider’s life is precious. Because the ten seconds are.

The longer answer

There’s a spider on the wall of the bath, and you’re holding, without having decided to, the whole of its fate. Two moves are on offer. One is the flat of a folded newspaper: instant, certain, nothing left to think about, and no one in the world will ever know you made it. The other is the ten-second one—the glass lowered over it, the card slid slowly underneath so as not to catch a leg, the careful carry to the window, the shake-out into the cold. Same spider. Same you. The only difference is what you’re willing to spend when spending nothing is right there as an option.

I’ve come to think these are the truest moments we get, precisely because they’re so small. The large moral occasions arrive with an audience, or at least with stakes big enough to summon your best self up to the front. Nobody is watching the bath. Nothing hangs on it. There’s no credit to earn and no penalty to duck, and into that little vacuum your actual character walks, unguarded, and does whatever it does. What you are when it doesn’t matter is what you are.

And the test is always the same one, whatever the creature: a thing wholly in your power, unable to resist and unable to report. The spider today; the tone you take with someone who can’t answer back; the care or carelessness you show a borrowed tool, a stray, a person you’ll never see again. Power without a witness is the one condition that can’t be faked, because there’s no one to fake it for. The reflex you bring to it is simply the truth about you, arriving before your opinion of yourself can get there to dress it up.

So I lower the glass, most days. Not out of any theory about the rights of spiders, which I don’t hold and couldn’t defend. I do it because I’d rather be the kind of hand that reaches for the glass, and the only way to be that kind of hand is to reach for it now—when it costs ten seconds and no one is looking, which turns out to be the only place such things are ever really decided.

Whether the spider is grateful, or even the wiser for it, I can promise you it is not. It bolts off into the cold to do spider things and forgets me at once. The ten seconds were never for the spider. It may be so. It may not.