A dash of classic logic



Comment on the document from the so-called “intelligence” services of the Ministry of Justice and Public Security

All men are mortal.
Socrates is a man.
Socrates is mortal.

This is perhaps the best-known syllogism in Western thought for its clarity and simplicity in establishing a necessary logical relationship between a principle and its consequence or between a cause and its effect, thanks to the inherence of a particular (Socrates) in a universal (all men) through the predicate that links them (mortals/mortal).

However, Aristotle considered that the perfect scientific syllogism is one in which the premises and conclusion are universal and affirmative. For example:

All the stars move.
All planets are stars.
All planets move.

Now, in recent days, the so-called “intelligence” services of the Ministry of Justice and Public Security have produced an apparently perfect syllogism by presenting a list of citizens considered subversive. As the dictionaries teach, subversion means opposition to the prevailing order and, therefore, the list refers to people contrary to the prevailing order. At first glance, syllogism would be as follows:

All subversives are against the prevailing order.
All Democrats are subversives.
All democrats are against the current order.

However, the logical imperfection of the syllogism above is found in the fact (emphasized by a historian friend of mine) that it is necessary to explain what the “current order” is, since the official document designates the subversives as anti-fascists and there can only be one anti-fascist subversive if the prevailing order is fascist, otherwise it cannot be called subversive. The correct form of the syllogism, therefore, is:

All anti-fascists are subversives.
All Democrats are anti-fascists.
All Democrats are subversives.

In summary: the authors of the official document, when introducing the idea of ​​anti-fascism as subversion, did not realize that they are obliged to implicitly affirm that the order currently in force in Brazil is fascist. They therefore incurred a glaring logical error, which generals Castello Branco, Geisel and Golbery would never have incurred.

As Hegel wrote: history repeats itself. The first time as a tragedy; in the second, as a farce.

*Marilena Chaui Professor Emeritus at the Faculty of Philosophy, Letters and Human Sciences at USP. Author, among other books, of invitation to philosophy (Rile up).

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