The thinker hardest to fool, and easiest to fool, is yourself

There was a knocking sound in the bakkie for about three weeks. A soft knock-knock from somewhere under the front, worse over bumps, worse when I turned. I had a whole case built for why it was nothing. It was the corrugations on our road. It was a water bottle rolling in the door. It was the heat. I presented this case, with real confidence, to my wife, to my brother, and most of all to myself — and it was airtight, watertight, completely convincing, held together by one quiet fact I never once said out loud: payday was two weeks off and a mechanic was the last thing we could afford.

The knock, it turned out, was not the road. But I want to stay a moment inside those three weeks, because in them I did something I would have sworn I was far too sharp to do. I fooled myself — expertly, thoroughly — without once noticing I was doing it.

We spend a lot of effort teaching children to spot other people's tricks: the advert, the con, the too-good deal, the friend talking them into something. All of it worth teaching. But it can quietly leave a child with the most dangerous idea of all — that being fooled is something other people do to you, from the outside, and that a sharp thinker is simply one with good enough defences to keep the tricksters out.

The trickster who slips past every defence is the one already inside — the part of you that has quietly decided how it wants the answer to come out.

Because the mind does not weigh evidence like a fair judge. It weighs it like a lawyer who already has a client. Once some part of us wants a thing to be true — that the noise is nothing, that we did fine in the test, that the person we dislike is as bad as we hoped, that our side was right all along — we don't stop reasoning. We reason harder. We get brilliant. We find every reason that points our way and wave off every reason that doesn't, and the whole performance feels, from the inside, exactly like honest thinking. That's the trap: motivated thinking doesn't feel like bias. It feels like being right.

There is no cure for this, and anyone who claims to have risen above it has merely been fooled by themselves about that too. There is only a habit, and it is a hard one: to grow most suspicious of your own thinking exactly when it is most convenient — when the conclusion happens to be the one you were hoping for. The question that saves you isn't "what's my evidence?" It's the harder one: "what would change my mind — and am I actually looking for it, or only hunting for reasons I'm already right?"

This is a teenager's lesson more than a small child's, and you teach it mostly by admitting your own. Say it out loud when you catch yourself: "I wanted that to be true, so I stopped checking." When your teenager is certain — gloriously, immovably certain — resist proving them wrong, and ask instead, "what would it take to change your mind?" If the honest answer is "nothing," you have both found the edge of thinking and the start of just wanting to win. Name it gently. Then admit the last time you were standing there yourself.

Which brings me back to the knocking.

It was a suspension part — not the road, not a bottle, not the heat. Cheaper to fix at three weeks than it would have been at six, which is the small joke the whole thing played on me: the self-deception I ran to save money cost more the longer it worked. I had been so busy building a case that the noise was nothing that I never asked the question a clear thinker asks first — what if I want this to be nothing because nothing is all I can afford?

I had caught a hundred adverts trying to fool me that month. The one that got through was the one I wrote, performed, and believed entirely by myself.

The thinker hardest to fool, and easiest to fool, it turns out, is yourself.