Thoughts on statements arising in Nisbett’s ‘Mindware’

While relaxing on a superb and inspirational three-week holiday in Japan …


… I began reading through a book that I’d purchased in January of this year, which I thought would provide some useful insights for my course – Mindware, by professor of psychology Richard Nisbett.

It’s … OK. I haven’t finished it yet. Interesting and insightful, broad coverage of the territory, long and wordy, would benefit from tighter editing.

But so far, I have discovered a couple of problems. The first one, on pp.228-229:

The shaky hold on logic characteristic of East Asians is evident today in the thinking even of young people studying in the best Asian universities.

Consider the three arguments below. Which seem to you to be logically valid?

Argument 1:
Premise 1: No police dogs are old.
Premise 2: Some highly trained dogs are old.
Conclusion: Some highly trained dogs are police dogs.

Argument 2:
Premise 1: All things that are made of plants are good for the health.
Premise 2: Cigarettes are things that are made of plants.
Conclusion: Cigarettes are good for the health.

Argument 3:
Premise 1: No A are B.
Premise 2: Some C are B.
Conclusion: Some C are not A.

The first argument is meaningful and has a plausible conclusion, the second argument is meaningful but its conclusion is not plausible, and the third argument is so abstract that it makes no contact at all with any real world facts. Despite the plausibility of its conclusion, argument 1 is invalid. Despite the implausibility of argument 2, it is valid. And the meaningless argument 3, as it happens, is invalid. (Try drawing Venn diagrams of these arguments to see how helpful they can be in assessing validity).

My problem is with Nisbett’s conclusion that Argument 3 is invalid. If ‘some C are B’, and ‘no A are B’, then it simply must be the case that some C – those that are B – are not A, because they cannot be A. Argument 3 must be valid. I’ve drawn out Venn diagrams to investigate this, and these point, I think, to the same conclusion.


Any logicians happening to pass by this blog, I would be grateful if you could either confirm that I am right, or show me where I am wrong.

The second problem appears on p.256:

Economists of the “rational choice” persuasion sometimes exhibit the same lack of constraint and circular reasoning as psychoanalytic, evolutionary, and learning theorists. All choices are rational because the individual wouldn’t have made the choice if he hadn’t thought it was in his best interests. We know the person thought it was in his best interests because that’s the choice the person made. The near-religious insistence that human choices are always rational leads such economists to make claims that are simultaneously untestable and tautological. The Nobel Prize-winning economist Gary Becker maintained that an individual who chooses to begin a career of drug addiction has to be considered rational if the individual’s chief goal in life is to satisfy a need for instant gratification. Facile, irrefutable, and circular. If drug addiction can be “explained” as rational behavior by a rational choice theorist, the theory is bankrupt in that person’s hands. All choices are known in advance to be rational, so nothing can be learned about the rationality of any given choice.

I disagree with this. My current thinking is that all people’s decisions are rational, in the sense that they seem optimal to the person at the time that they make them. Otherwise they wouldn’t make the decision, right? What this understanding does is open up the questions of why this behaviour, these decisions, are rational at the time for this person, and what makes some people’s behaviour different from that of others. One explanation that economists have come up with is differing time preference, and exponential and hyperbolic discounting. I am surprised, I would have thought a professor of psychology would have known about these things, or at least be interested in them.

I may be wrong – interested in your thoughts.


About Stebbing Heuer

A person interested in exploring human perception, reasoning, judgement and deciding, and in promoting clear, effective thinking and the making of good decisions.
This entry was posted in Decision-making, Esau Problem, Reasoning. Bookmark the permalink.

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