On Human Stupidity, part III - A Short Historical Perspective b

The literature on how our reasoning is far from optimal is already huge and it keeps growing everyday. I have no intention to even try to be comprehensive here. While the subject is very interesting, ultimately, this whole text of mine is about how we can try to get as close to good answers as possible. Answers about anything and that, of course, means something some people would call scientific method, despite the problems with that name. There are already good introductory texts to the psychological aspects of human reasoning, such as the two I mentioned in the first post of some history on human stupidity (Plous and Baron) and I strongly encourage anyone interested in the matter to read them and others as well as the many papers in dedicated journals and sites. Currently, there is a very nice list of online resources and academic journals at http://www.sjdm.org/links.html.


What I find crucial to understand is how limited we actually are. The examples here are for didatic purposes at educating people on this specific question and do not, by any means, replace the existing literature. As we will discuss later throughout the book and especially in the Chapter "The Real Strength of Science'', it is fundamental to know what the really serious scientific community is discussing. Not because it is correct, scientists who do understand Epistemology well should never actually make truth claims about the real world. But because Science is always the best answer we have at the moment. On a sidenote, I just love this phrase: ``It is therefore a truism, almost a tautology, to say that all magic is necessarily false and barren;  for were it ever to become true and fruitful, it would no longer be magic but science'' from James Frazer in the The Golden Bough.



And, of course, in order to illustrate our known failings, likely to be a characteristic of the Homo Sapiens species, I take to class not just the card problem, but a number of now classical examples of our human stupidity. The second traditional example of the psychological literature I like to present to my students is already based on probability evaluations. This example is now known as the Linda problem. The text I present them is this:



"Linda is 31 years old, single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear demonstrations. Which of the following two alternatives is more probable?

1. Linda is a bank teller.
2. Linda is a bank teller and active in the feminist movement.'' Tversky and Kahneman, 1983.

It is obvious after careful inspection that if the second alternative is true, the first must also be. Therefore we can easily prove that the first alternative must be more probable than the second. Equality would be theoretically possible, but it would demand that we are absolutely sure that, if Linda is a bank teller, there is no chance at all she wouldn't be active in the feminist movement. So, despite mentioning probabilities, the answer is known for certain here.



Amazingly, many people get somehow drawn by the word feminist in the second phrase, that seems to fit Linda description better and pick the second alternative. But the question is not if she is more likely to be a feminist or a teller. While the exact reason we do it is not completely clear, for me, there is some amount of evil fun in watching the faces of students realizing they are failing miserably in trivial problems. That their intuition can not be trusted at all. This is a lesson I can only wish they will carry through their lives, allowing them to be much more careful in their reasoning. And, hopefully, better at the decision making and judgement problems they will face in their lives.



Examples of our failure are numerous. And, while this previous example had a certain answer, it does raises the question that, in real life, it is quite common that the best we can hope to achieve in a specific situation is a solid probabilistic assessment of the problem. Which brings us to the question of how we deal with problems where there is uncertainty of some kind. Remember, we already fail where there is certainty to be had. Try to guess how we, as a species, will fare next, when we check what is know about probabilistic reasoning.


#reasoning #biases