The Delusion of Reason

Scottish Enlightenment philosopher David Hume (1711-1776) wrote that:

“Reason is, and ought only to be the slave of the passions, and can never pretend to any other office than to serve and obey them.”

Treatise on Human Nature

This is a radically different view than most of us have about thinking, reason, and how our minds work – who and what we are. I don’t know that I agree 100% with Hume, but he was definitely on to something important.

We think of our reason and our mind as being in charge of things. Hume says not really. Our mind is more like a lawyer that tries to justify and defend the desires of the passions.

Another useful analogy is that of an elephant and a rider from the work of social psychologist Jonathan Haidt. The rider is the conscious mind and the elephant is all of that below consciousness; emotions, instincts, intuitions, and who really knows what else – much perhaps the product of physical and social evolution.

The rider and the elephant

The elephant is much more powerful than the rider. The rider often uses reason not to guide our actions, but to justify them after the fact.

The rider, like a lawyer, is very prone to seeking out that which justifies the actions and beliefs of the elephant rather than trying to look objectively at all the facts before coming to a conclusion. Often our conclusions are a foregone conclusion. This is called confirmation bias:

“Confirmation bias is the tendency to search for, interpret, favor, and recall information in a way that affirms one’s prior beliefs or hypotheses. It is a type of cognitive bias and a systematic error of inductive reasoning. People display this bias when they gather or remember information selectively, or when they interpret it in a biased way. The effect is stronger for desired outcomes, for emotionally charged issues, and for deeply-entrenched beliefs.


Everyone is susceptible to some degree to the confirmation bias. In the New Testament Jesus says:

“… why do you look at the speck in your brother’s eye, but do not consider the plank in your own eye? Or how can you say to your brother, ‘Let me remove the speck from your eye’; and look, a plank is in your own eye? Hypocrite! First remove the plank from your own eye, and then you will see clearly to remove the speck from your brother’s eye.”

Matthew 7:3-5 New King James Bible

As humans we are very good at seeing the defects in the reasoning of others. Because of the confirmation bias we are not so good at seeing the defects in our own reasoning. If people can work together respectfully and be willing to accept constructive criticism this negative can be turned into a virtue. The collective reasoning can be used to find the flaws the individual often cannot see.

This is how science is supposed to work (but sometimes does not!). Even well-trained scientists are susceptible to confirmation bias. This is the purpose of rigorous peer review in science. When many minds with different biases look at the same problem the weak conclusions are winnowed out and the collective view that emerges is more likely to mirror reality.

Jesus is right that we need to find the “planks” in our own eyes. It is difficult and will take some time to re-train the elephant!

This is where I disagree with Hume. He was absolutely right that we have a strong tendency to use reason to justify our passions. What I don’t think he allowed for was that we can change and the rider can learn to have much greater influence over the elephant. I didn’t say that would be easy, did I?

Copyright © 2019 Lawrence W. Kennon