Whether you know it or not, you’re a natural nonfiction writer. In fact, you create narratives about the world that are more or less true every day of your life. Don’t believe me? Take a look at the picture above.

That’s my dog, Bo. He’s a four-year-old Labrador Retriever. Based only on that information and the picture above, your brain has already begun to tell you a tale about Bo–and probably about me, too.

Based on your previous experience with dogs, your tale may assume that Bo barks and jumps on the furniture, or that he runs to greet my daughters when they get home from school. It may insist that he hates cats or mailmen, or that he loves chewing rawhide “bones.” It may characterize him as friendly or dangerous, as partial to snuggling or prone to pouncing, as warm and fuzzy or hairy and dirty, as completely adorable or likely deplorable. Based on the picture above, it may assume that he likes to be on the sofa, or that he only longs to be outside.

In any case, before you ever stop to reflect on what you actually know about Bo, your brain has started to draft a story in which to place him. If you’re smart (and you are, or you wouldn’t be reading this) you’ll readily realize that this story is based almost entirely on assumptions. But that won’t stop your brain from drafting it–or from thereby predisposing you to see both Bo and me in certain ways.

That’s how brains work. They start seeking out connections and conclusions long before they start actually weighing the evidence. In fact, it’s rare that they get around to much weighing of the evidence at all.

Think about it: whatever assumptions your brain began to make about Bo, I’m guessing none of them included the caveat “this snapshot of Bo represents only a tiny, tiny fraction of his life.” Or, “I’ve heard that Labrador retrievers have certain characteristics, but I’ve only ever met a few of them.” Or again, “my own fear (or love) of dogs is bound to color how I see this one, even though that isn’t really fair.”

My point here is not to criticize you for “judging” my dog–either for the worse or for the better (and believe me, he can be both). My point is that you really don’t have any choice in the matter. Our brains are assumption engines–snap judgers and storytellers. They have to be to get us through the world. By the time we stop to reflect, if we ever do, they have already categorized and organized and storified what they see. And they then often use what reason they have to defend their previous, unreflective choices rather than to critique themselves.

Put another way: Your mind doesn’t naturally operate like a good scientist, looking for ways to poke holes in the stream of evidence presented to it. It operates more like a reporter on a tight deadline, weaving together what facts it can find to draft the best story it can. Then, once it’s gone to press, it gets a little testy if you criticize what it’s written.

The implications of this model of mentation are profound. For one, you generally shouldn’t assume that what your mind tells you at any given moment is the truth, the whole truth, and nothing but the truth. Assume instead that it’s the best report your mind could create based on current evidence, interpreted in light of past experience, in time to meet an ever-pressing deadline. A mind with more time, different evidence, and/or better writing skills might tell the story differently–and so might your own mind if and as conditions change.

What’s more, if you want to strengthen your own thinking, you have to learn to be your own mind’s editor. You have to demand that it corroborate its facts and validate its sources. You have to help it spot its biases and the places where it jumps to conclusions. You have to push it to dig deeper, ask more and better questions, eliminate errors, and use only the most appropriate words, phrases, and structures to tell its stories.

You don’t have to make your mind something it fundamentally isn’t–a “mirror of nature,” say, or a purely objective computational device. But you can and should make it a better nonfiction writer: a creator of stories that are simultaneously truer and more compelling, and therefore a better author of your experience.