How Different would we Be if we could See our Logical Fallacies?


Logic takes a hit on January 21st, 2015 on SZ. com. Anyone see my toupee?

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Nick built a time machine :scream_cat:

Ha, ha, you caught my mistake.

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These are good to know… I sometimes wish the medieval style curriculum of the bachelor would still be available, which consisted of only Logic, Grammar, and Rhetorics. Those guys would have known these by heart.

It is funny though, as a student of logic and philosophy, a lot of my courses are on formal logic, but even there we are not taught to learn these by heart. I wouldn’t be able to name most of them, but I think I could point them out though.

Since the topic interests me, and SZ does as well, the link between the two is of interest to me as well - as in, do we schizophrenics operate on a different logic? There is some interesting research available on the topic, which sometimes turns out to be, to me, rather surprising.

First it should be noted that ordinary ‘neurotypicals’ are far from immune to fallacies in logic. The rules of inference, as displayed by the neurotypical population, do not coincide with the norms of classical logic, which the fallacies suppose. Rules of logic are sometimes called prescriptive, or normative, whereas the patterns that are actually to be found in the neurotypical population are descriptive of actual reasoning ‘in the wild’. Classical logic prescribes how one ought to reason, the results of psychological studies on this show how people actually reason. And when one compares the two, one can be rather surprised, or shocked.

A famous example is the Wason-selection task:

If I recall correctly, out of a neurotypical population, only 10-20% applies the strategy that is the correct one according to classical logic (when the task is presented in abstract fashion). This has been taken to mean that people are largely illogical. During the second half of the 20th century though, logic came to get a bit of a broader meaning. Many different logics were established. I.e., logic did not quite have the eternal/sublime status it once had, as displaying the fundamental rules of what is/could be, but rather, people came to realize one could as well formalize systems of inference rules that differ from those of classical logic. As such, nowadays one can hardly speak of ‘the’ rules of logic. For there are logics where, e.g., the implication has a different meaning, different truth conditions, than in the classical approach. Accordingly, the deviant approaches to the Wason-selection task that did not coincide with the classical logical solution have been shown to do demonstrate systematic reasoning. Different strategies have also been formalized into a logic that accordingly approaches and tries to formalize the logic people actually use. Such that, though having parted ways in the late 19th/early 20th century, psychology and logic may become relevant to each other once more.

Be that as it may, this Wason-selection task was also performed by schizophrenic and autistic populations, in comparison with the neurotypical population. The rather remarkable outcome was that schizophrenics and autists showed an equal or greater preference for the ‘logically correct’ strategy of solving the puzzle than neurotypicals, though not in all cases. For it is well known, that the task can be made easier when cast into a bit of a story, rather than leaving it abstract with letters and numbers. Neurotypicals get ‘bettter’ at the task as it increasingly resembles a real-life situation. Schizophrenics do not. In the most abstract version, schizophrenics are not worse at this reasoning task than neurotypicals are. (This can be found in Dudley, 1997).

A wholly different study, which also has some interesting results and discussion of logic and reasoning in schizophrenia in comparison to neurotypicals is the following.

In short, this study showed that schizophrenics tend to be better at a specific reasoning task. The task is on syllogistic reasoning, where two premises are presented, which are to be assumed true, and a conclusion that either does or does not follow from these premises. The task was to eveluate the validity of the argument presented.

The remarkable result was, that when the argument included a conclusion that is actually or intuitively true, yet which did not logically follow from the presented premises, schizophrenic patients demonstrated a greater sensitivity to the invalidity of such arguments. That is to say, the neurotypical population let their intuitions overrule the rules of classical inference more so than the schizophrenic population. The neurotypicals seemed to evaluate the argument as valid as long as the conclusion matched up with their background knowledge, whereas the schizophrenic population had less difficulty assessing the actual inference that was made.

To me, such studies put accounts of delusion that hinge on erroneous reasoning in another perspective. The counterintuitive arguments, and the abstract versions of the Wason selection task, are evaluated/solved equally or more ‘logically’ by schizophrenics in comparison to neurotypicals. This seems to me to point to not so much a reasoning deficit per se.


In my experience of observing “sz logic” both en vitro (here) and en vivo, I would say that there’s a very noticeable skew towards a more absolutistic, totalistic, all-or-nothing, all-good-vs-all-bad, absolute-good-vs-absolute-evil, black-or-white thinking in those who have any of the psychotic spectrum disorders.

But I am also intrigued by the degree to which people who do not meet diagnostic criteria for such disorders may selectively display logical fallacies with respect to say, politics or religion. In those realms, it looks to me like social proof and resulting normalization to irrationality is a big factor in why this occurs.

A whole shelf of books I have read on the families of sz patients supports the notion of social proof normalization of illogic in the minds of sz patients.

Bateson, G., Jackson, D., Haley, J.; et al: Perceval’s Narrative: A Patient’s Account of his Psychosis, Palo Alto, CA: Stanford University Press, 1961.

Esterson, A.: The Leaves of Spring: Schizophrenia, Family and Sacrifice, London: Tavistock, 1972.

Henry, J.: Pathways to Madness, New York: Random House, 1965.

Jackson, D. (ed.): The Etiology of Schizophrenia: Genetics / Physiology / Psychology / Sociology, London: Basic Books, 1960.

Jackson, D.: Myths of Madness: New Facts for Old Fallacies, New York: Macmillan & Co., 1964.

Laing, R. D.; Esterson, A.: Sanity, Madness and the Family, London: Tavistock, 1964.

Lidz, T.: The Origin and Treatment of Schizophrenic Disorders, New York: Basic Books, 1973.

Lidz, T.; Fleck, S., Cornelison, A.: Schizophrenia and the Family, 2nd Ed.; New York: International Universities Press, 1985.

Scharff, J. S.: Foundations of Object Relations Therapy, London: Jason Aaronson, 1989.

And the roads out of such illogic appear to be collegiate critical thinking (see below), the CBTs and some of the MBCTs.

REBT – Rational emotive behavior therapy - Wikipedia
Schematherapy – Schema therapy - Wikipedia
Learned Optimism – Learned optimism - Wikipedia
Standard CBT – Psychotherapy | NAMI: National Alliance on Mental Illness & scroll down
MBBT – An Introduction to Mind-Body Bridging & the I-System – New Harbinger Publications, Inc
10 StEP – Pair A Docks: The 10 StEPs of Emotion Processing