Here’s one of the most thought-provoking quotes I read recently:
Reasoning was not designed to pursue the truth. Reasoning was designed by evolution to help us win arguments.
We think we use reason to enhance decisions making and improve knowledge. But more often that not, when we think we are reasoning, we are merely trying to rationalize a conclusion that we’ve already made. Reasoning often equates to justifying an existing belief as opposed to getting at a better belief.
A recent white-paper proposes a hypothesis that the function of reasoning is not truth-seeking but argumentative. We use reasoning to devise and evaluate arguments for persuading others and ourselves. They conclude that while reasoning makes human communication more effective and potent, it not only falls short of delivering rational beliefs and rational decisions reliably, but it may even be detrimental to rationality in many cases.
This explains why humans reason rather poorly, and are vulnerable to cognitive biases such as confirmation bias.