Morris Raphael Cohen (1880-1947) was an American philosopher of naturalist bent who taught at the City College of New York from 1912 to 1938. He was reputed to have been an outstanding teacher. I admire him more for his rationalism than for his naturalism. In the early 1990s, I met an ancient lady at a party who had been a student of Cohen's at CCNY in the 1930s. She enthusiastically related how Cohen had converted her to logical positivism, and how she had announced to her mother, "I am a logical positivist!" much to her mother's incomprehension.
…the exercise of thought along logical lines is the great liberation, or, at any rate, the basis of all civilization. We are all creatures of circumstance; we are all born in certain social groups and we acquire the beliefs as well as the customs of that group. Those ideas to which we are accustomed seem to us self-evident when [while?] our first reaction against those who do not share our beliefs is to regard them as inferiors or perverts. The only way to overcome this initial dogmatism which is the basis of all fanaticism is by formulating our position in logical form so that we can see that we have taken certain things for granted, and that someone may from a purely logical point of view start with the denial of what we have asserted. Of course, this does not apply to the principles of logic themselves, but it does apply to all material propositions. Every material proposition has an intelligible alternative if our proposition can be accurately expressed.
These are timely words. Dogmatism is the basis of all fanaticism. Dogmatism can be combatted by the setting forth of one's beliefs as conclusions of (valid) arguments so that the premises needed to support the beliefs become evident. One can also show by this method that arguments 'run forward' can just as logically be 'run in reverse,' or, as we say in the trade, 'One man's modus ponens is another man's modus tollens.'
In Cohen's day, the threats to civilization were Fascism, National Socialism, and Communism. Today the threat is Islamo-totalitarianism. Then as now, logic has a small but important role to play in the defeat of these threats. The fanaticism of the Islamic world is due in no small measure to the paucity there of rational heads like Cohen.
But I do have one quibble with Cohen. He tells us that "Every material proposition has an intelligible alternative…" (Ibid.) This is not quite right. A material proposition is one that is non-logical, i.e., one that is not logically true if true. But surely there are material propositions that have no intelligible alternative. No color is a sound is not a logical truth since its truth is not grounded in its logical form. No F is a G has both true and false substitution-instances. No color is a sound is therefore a material truth. But its negation Some color is a sound is not intelligible if 'intelligible' means possibly true. If, on the other hand, 'intelligible' characterizes any form of words that is understandable, i.e., is not gibberish, then logical truths such as Every cat is a cat have intelligible alternatives: Some cat is not a cat, though self-contradictory, is understandable. If it were not, it could not be understood to be self-contradictory. By contrast, Atla kozomil eshduk is not understandable at all, and so cannot be classified as true, false, logically true, etc.
So if 'intelligible' means (broadly logically or metaphysically) possibly true, then it is false that "Every material proposition has an intelligible alternative . . . ."