I’m pretty sure you and I are on the same page.

As smart, hard-working people who want to get smarter, we’re on a lifelong quest for personal development. No, we’re not into woo-woo mysticism or law-of-attraction nonsense, but we are interested in making a conscious effort to get better at life. We want to improve, not just pass the time.

And if we want to get better at life, we must learn to make better decisions. That means learning to recognize a major cause of poor decisions: cognitive biases.

What are cognitive biases? Let me show you.

After hunting high and low for a good definition of cognitive bias, I’m prepared to admit that my favorite comes from Wikipedia:

A cognitive bias is a systematic pattern of deviation from norm or rationality in judgment.

This is a great definition, but we can go further and actually watch a cognitive bias in action right now. Here, I turn to an example from Daniel Kahneman’s masterpiece Thinking, Fast and Slow. Consider the following scenario:

You are offered a gamble on the toss of a coin. If the coin shows tails, you lose $100. If the coin shows heads, you win $150. Is this gamble attractive? Would you accept it?

The odds are 50/50 here. Heads, you win $150. Tails, you lose, but only $100. The rational move is clear: take the wager!

Yet most of us would turn down this gamble due to a cognitive bias called loss aversion: we tend to prefer avoiding a loss to acquiring an equivalent gain. It’s not rational, but it’s how we’re wired. And while we’re perfectly capable of rational thought, the real doozy is this: unless we’ve studied cognitive biases, we’re not even aware they’re affecting our thinking. They’re just sneaking around in our mental architecture like computer viruses.

Devious! So where do these pesky things come from?

What causes cognitive biases?

In a 2015 paper titled “The Evolution of Cognitive Bias,” evolutionary psychologists Martie G. Haselton, Paul W. Andrews, and Daniel Nettle lay out three causes of cognitive biases:

Cognitive biases can arise for three reasons: Selection may discover useful shortcuts that tend to work in most circumstances, though they fall short of some normative standards (heuristics); biases can arise if biased solutions to adaptive problems resulted in lower error costs than unbiased ones (error management biases); and apparent biases can arise if the task at hand is not one for which the mind is designed (artifacts).

In other words, cognitive biases arise when our brains take one-size-fits-all shortcuts, decide that the end justifies the means, or have to make the best of situations where they’re out of their depth. Our brains, like the rest of our bodies, are doing their best under the circumstances. But they can’t do everything perfectly.

What do we do about these lousy things?

Bad news first: we can’t eradicate cognitive biases. They’re unwanted by-products—functions of how effective our brains are at so many other tasks and processes. The tendency to make certain kinds of poor decisions will always be part of us, like weeds in a fertile vegetable garden.

But there’s good news, too! We can train ourselves to recognize and avoid cognitive biases in our own thinking, like a gardener who learns to identify common weeds and pulls them when she sees them. To that end, I’ve written a couple of articles on cognitive biases—one on hindsight bias and another on the false consensus effect—and I’ll be writing more in the future.

While we’ll never become fully rational thinkers, we can improve our conscious decision-making quite a bit. And since a good portion of our lives is out of our control, it’s that much more important that we do our absolute best with what we can control.

It’s amazing what a little weeding can do.

For the definitive layman’s book on this subject, check out Daniel Kahneman’s Thinking, Fast and Slow. Kahneman, together with Amos Tversky, did much of the pathbreaking work on cognitive biases. Charlie Munger’s famous 1995 speech “The Psychology of Human Misjudgment” is also excellent (and entertaining).