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Friday, April 25, 2014


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>>First of all this is a howling non sequitur:

1. Logic does not study mental processes;
2. Logic studies visually perceptive signs.

Yes, but Lukasiewicz does not make this inference. He states (1) that logic is the not the science of the laws of thought, and that “the laws of logic do not concern your thoughts in a greater degree than do those of mathematics”.

And he does not say that “Logic studies visually perceptive signs”. Rather, that the aim of logic is to attain the greatest possible exactness by means of a precise language built up of stable, visually perceptible signs.

Expressing his argument as I understand it.

(A) The main object of logic is to establish criteria for valid reasoning.

(B) Such criteria are a body of scientific truth.

(C) Every scientific truth in order to be perceived and verified, must be put into an external form intelligible to everybody.

(C) Thought processes, when not formed in words and bearing an external shape, are accessible only to a clairvoyant, and thus not in a form intelligible to everybody.

(D) There can be no scientific truths about thought processes, unless they are formed in words and bearing an external shape.

(E) Logic, insofar as it is a science, is the science involving thoughts qua ‘bearing an external shape’. In particular, any ‘criterion of validity’ can be applied only to the form of external material such as written and spoken words.

>>The meaning (the proposition), is not identical to the physical string.

Correct. It is the form that thought takes when expressed in the physical string. But that form must be observable. Your example of the Turkish “Yash yetmis ish bitmish” is like colour-blindness. Some people cannot distinguish red from green. They are colour-blind. Sometimes they can learn to distinguish. Other times they can have medical treatment. The cure for meaning-blindness is simpler: learn the language. In this case, learn Turkish. Then you can perceive a form that was always there, but not apprehensible to all.

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