I had dinner with Kahneman once a few months ago, and have now been dipping into his deep and thoughtful book Thinking, Fast and Slow.

Though I haven’t read all of it, I begin to realize that though he and I both sometimes use the word intuition, we are talking about different qualities.

For Kahneman, I think, intuition is fast thinking, snap judgements, attractive because they avoid hard rational thinking of the second kind. As a result, it’s riddled with biases and mistakes which are interesting to psychologists.

But I once was a physicist and I’m still interested in the mysteries of nature, and so I use the word intuition in another sense. I like to think I’ve had a few occasional intuitions that were correct in small ways about small things while doing research, so I’m talking from experience. When they were right, they were the result of long hard exhausting preliminary rational struggles, banging one’s mind against the object of one’s attention. Then, finally, once in a few years, came an insight or idea or intuition, after all the struggle, that still had to elaborated by further rational effort. That’s what I call intuition.

Kahneman’s and mine are both legitimate uses of the word, but different ones.

A few remarks

Kahneman’s “intuition” = a quick guess; I mean by intuition the insight that can come only after long mental struggles.

Kahneman is concerned with the biases of intuition. I am impressed with its occasional glimpses of absolute essence. Think Newton, Ampere, Maxwell, Einstein, Feynman, Spinoza or Freud or Schopenhauer maybe … That kind of intuition plays a major role in the discovery of nature’s truths.

Intuition is comprehensive. It unifies the subject with the object, the understander with the understood, the archer with the bow. Intuition isn’t easy to come by, but is the result of arduous struggle.

In both physics and finance the first major struggle is to gain some intuition about how to proceed; the second struggle is to transform that intuition into something more formulaic, a set of rules anyone can follow, rules that no longer require the original insight itself.

Intuition: From Models.Behaving.Badly

It takes intuition to discover theories. Intuition may sound casual, but it emerges only from intimate knowledge acquired after careful observation and painstaking effort. Before you can move one level higher in the pyramid of understanding, before you can attain intuition in some domain, you have to struggle with the particulars of that domain until knowledge of its details is second nature to you.

A cyclist develops physical intuition about the correct angle to tilt body and bicycle to a curved track so as to maximize stability; the builder of a velodrome can calculate the correct banking angle to ensure the cyclist remains in equilibrium; together biker and builder combine visceral and theoretical knowledge. Intuition is learning to ride a bicycle without thinking. You have to incorporate the laws of the world into your body.

Feynman’s insight into the parallel evolution of quantum mechanical paths, Dirac’s grasp of the essence of electrons, Newton’s understanding of mass and its motion—all are instances of the external world joining with the internal. Intuition is a merging of the understander with the understood. In the words of the Upanishads, Tat Tvam Asi, Thou art that.

The Insightful Keynes on The Great Newton Sees Intuition the Way I Do: