Humans 101

Believing Is Easy, but Being Correct Is Difficult

Our fast brains are gullible, and our slow brains can fix things up… when they get around to it

Sam Brinson
Human Parts
Published in
8 min readJun 25, 2020


Blue reflection of person drinking from cup.
Photo: Johner Images/Getty Images

When you encounter new information but have yet to form a belief about it, what’s your immediate response? Do you hold it up in your mental spotlight and subject it to a critical analysis? Do you suspend your belief until you’ve either confirmed or denied it?

We have limited time and mental resources to properly evaluate everything that impinges on our minds. We don’t stop to fact-check every headline that passes by on social media or every claim made by certain news outlets or each idea presented in a book.

What happens to things we encounter but don’t critically analyze? Research suggests that they can slip into our “truth baskets.” Once there, they can persist rather stubbornly.

Believing, it turns out, is the easy part. The second step is where things get tricky.

The library of belief

René Descartes wrote, “All that the intellect does is to enable me to perceive, without affirming or denying anything, the ideas which are subjects for possible judgments.” To Descartes, the mind is supposed to hold ideas up to be examined, to keep them in limbo until a decision about their accuracy is made.

Baruch Spinoza had a different idea. He thought that by perceiving or comprehending something we implicitly believe it first, and only through an extra step can we disconfirm it. William James, writing on Spinoza’s position, said, “All propositions, whether attributive or existential, are believed through the very fact of being conceived.”

In this account, if we don’t have the time or energy to critically consider the information impinging on our mind, we’re at risk of accepting it as true. Belief is the first step, evaluation the second.

Psychologist Dan Gilbert uses a library metaphor to understand the two ideas. Imagine you have a library: Most of the books are nonfiction, but there are a few fiction books in there too. To distinguish between them, you decide to tag the spines of the books, using one of two systems.



Sam Brinson
Human Parts

An emergent property of billions of chaotically firing neurons. Currently thinking about thinking.