Daniel Kahneman on Experts

When should you trust an expert’s empirical predictions? Says Daniel Kahneman in Thinking Fast and Slow:

When do judgments reflect true expertise? When do they display an illusion of validity? The answer comes from the two basic conditions for acquiring a skill:

  • an environment that is sufficiently regular to be predictable
  • an opportunity to learn these regularities through prolonged practice

When both these conditions are satisfied, intuitions are likely to be skilled. Chess is an extreme example of a regular environment, but bridge and poker also provide robust statistical regularities that can support skill. Physicians, nurses, athletes, and firefighters also face complex but fundamentally orderly situations. The[ir] accurate intuitions… are due to highly valid cues that the expert’s [intuitive] System 1 has learned to use, even if [the rational] System 2 has not learned to name them. In contrast, stock pickers and political scientists who make long-term forecasts operate in a zero-validity environment. Their failures reflect the basic unpredictability of the events that they try to forecast….

Some regularities in the environment are easier to discover and apply than others. Think of how you developed your style of using the brakes on your car. As you were mastering the skill of taking curves, you gradually learned when to let go of the accelerator and when and how hard to use the brakes. Curves differ, and the variability you experienced while learning ensures that you are now ready to brake at the right time and strength for any curve you encounter. The conditions for learning this skill are ideal, because you receive immediate and unambiguous feedback every time you go around a bend: the mild reward of a comfortable turn or the mild punishment of some difficulty in handling the curve if you brake either too hard or not quite hard enough. The situations that face a harbor pilot maneuvering large ships are no less regular, but skill is much more difficult to acquire by sheer experience because of the long delay between actions and their noticeable outcomes. Whether professionals have a chance to develop intuitive expertise depends essentially on the quality and speed of feedback, as well as on sufficient opportunity to practice….

Some aspects of any professional’s tasks are much easier to learn than others. Psychotherapists have many opportunities to observe the immediate reactions of patients to what they say. The feedback enables them to develop the intuitive skill to find the words and the tone that will calm anger, forge confidence, or focus the patient’s attention. On the other hand, therapists do not have a chance to identify which general treatment approach is most suitable for different patients. The feedback they receive from their patients’ long-term outcomes is sparse, delayed, or (usually) nonexistent, and in any case too ambiguous to support learning from experience.

Among medical specialties, anesthesiologists benefit from good feedback, because the effects of their actions are likely to be quickly evident. In contrast, radiologists obtain little information about the accuracy of the diagnoses they make and about the pathologies they fail to detect. Anesthesiologists are therefore in a better position to develop useful intuitive skills.

Mises on God?

An interesting quote on theology from Mises’s Human Action:

Scholastic philosophers and theologians and likewise Theists and Deists of the Age of Reason conceived an absolute and perfect being, unchangeable, omnipotent, and omniscient, and yet planning and acting, aiming at ends and employing means for the attainment of these ends. But action can only be imputed to a discontented being, and repeated action only to a being who lacks the power to remove his uneasiness once and for all at one stroke. An acting being is discontented and therefore not almighty. If he were contented, he would not act, and if he were almighty, he would have long since radically removed his discontent. For an all-powerful being there is no pressure to choose between various states of uneasiness; he is not under the necessity of acquiescing in the lesser evil. Omnipotence would mean the power to achieve everything and to enjoy full satisfaction without being restrained by any limitations. But this is incompatible with the very concept of action. For an almighty being the categories of ends and means do not exist. He is above all human comprehension, concepts, and understanding. For the almighty being every “means” renders unlimited services, he can apply every “means” for the attainment of any ends, he can achieve every end without the employment of any means. It is beyond the faculties of the human mind to think the concept of almightiness consistently to its ultimate logical consequences. The paradoxes are insoluble. Has the almighty being [p. 70] the power to achieve something which is immune to his later interference? If he has this power, then there are limits to his might and he is no longer almighty; if he lacks this power, he is by virtue of this fact alone not almighty.

Quote: Isaiah Berlin

From Two Concepts of Liberty:

I am the possessor of reason and will; I conceive ends and I desire to pursue them; but [when] I am prevented from attaining them I no longer feel master of the situation. I may be prevented by the laws of nature, or by accidents, or the activities of men, or the effect, often undesigned, of human institutions. These forces may be too much for me. What am I to do to avoid being crushed by them?  I must liberate myself from desires that I know I cannot realise. I wish to be master of my kingdom, but my frontiers are long and insecure, therefore I contract them in order to reduce or eliminate the vulnerable area. I begin by desiring happiness, or power, or knowledge, or the attainment of some specific object. But I cannot command them. I choose to avoid defeat and waste, and therefore decide to strive for nothing that I cannot be sure to obtain. I determine myself not to desire what is unattainable.


In a world where a man seeking happiness or justice or freedom (in whatever sense) can do little, because he finds too many avenues of action blocked to him, the temptation to withdraw into himself may become irresistible. It may have been so in Greece, where the Stoic ideal cannot be wholly unconnected with the fall of the independent democracies before centralized Macedonian autocracy. It was so in Rome, for analogous reasons, after the end of the Republic. It arose in Germany in the seventeenth century, during the period of the deepest national degradation of the German States that followed the Thirty Years War, when the character of public life, particularly in the small principalities, forced those who prized the dignity of human life, not for the first or last time, into a kind of inner emigration. The doctrine that maintains that what I cannot have I must teach myself not to desire, that a desire eliminated, or successfully resisted, is as good as a desire satisfied, is a sublime, but, it seems to me, unmistakable, form of the doctrine of sour grapes: what I cannot be sure of, I cannot truly want.

Quote: Robert Nozick

From the Preface of Anarchy, State, and Utopia, with elisions.

Many persons will reject our conclusions instantly, knowing they don’t want to believe anything so apparently callous toward the needs and suffering of others.  I know that reaction; it was mine when I first began to consider such views.  With reluctance, I found myself becoming convinced….  I run the risk of offending doubly: for the position expounded, and for the fact that I produce reasons to support this position.

My earlier reluctance is not present in this volume, because it has disappeared.  Over time, I have grown accustomed to the views and their consequences….

It is thought to be an objection to other views merely to point out that they conflict with the view which readers wish anyway to accept.  But a view which differs from the readers’ cannot argue for itself merely by pointing out that the received view conflicts with it!  Instead it will have to subject the received view to the greatest intellectual testing and strain, via counterarguments, scrutiny of its presuppositions, and presentation of a range of possible situations where even its proponents are uncomfortable with its consequences.

Quote: Post Series

Since I’m using the blog as a public archive of sorts, I thought I’d start another series that I’ve been meaning to keep.  The posts in this series will consist of just the quote, with maybe a sentence of context.  As with my “Worth Reading” series, I don’t intend selection of a quote necessarily to be an endorsement of its sentiment.