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logical mythconceptions

so crasstoise asked me to expand on this post about what logic actually is vs what people usually think that it is.

i was going to do some research so that I could lay out a careful explication between the difference of the colloquial ‘logic” versus logic as philosophical endeavour. but it would take more effort right now than i really feel like1. and anything I say here can be fact checked without too much effort.

What most people think logic is, or what people think the property ‘logical” means is, more or less, ‘making sense”

in everyday use, the demand that someone be ‘logical” is the demand that they make sense in some important respect. similarly a call to ‘logic” is a call for the person to be ‘coherent”. it might actually be a call for someone to be ‘rational”.

So. We can see here that ‘logical” is normative in its application in everyday life, it is intended to demand that people make sense. but, one might ask: ‘how, exactly, is this different from the rules of language? since the grammatical, syntactical, and phonetic rules of language are what make it comprehensible to the community of users”.

In most cases this is what people have in mind when the use ‘logic” in an everyday setting. That they want someone or something to ‘make sense”.

Yeah, so how does logic differ from the philosophy of language? logic differs by being more strict in its rules on what makes sense and what doesn”t. the rules of natural language are pretty permissive in what can be considered comprehensible2. logic narrows its focus on elements of natural language called ‘logical operators”. There are four common ones in english: if/then, and, or, not. But, for sound and valid systems of logic, like classical logic, you only actually need to of the operators.

Logic these days, goes even further, doing away with those pesky words and replacing them with symbols and variables. It, ultimately, doesn”t care about the content of arguments, only their forms. It focus on syntax (the rules governing how you can combine variables and operators) and semantics (the assignment of truth values to variables and formulae)3.

And that is what logic is today: variables, symbolic logical operators, syntax, and semantics4.

In this sense, something is ‘logical” insofar as it has those elements, if it does not have those elements, it is not logic/al5.

So, obviously, when your average everyday person demands that you be ‘logical” in speech or deed, the clearly are not asking you to present your speech or deeds with variables, symbolic logical operators, with some specific syntax and semantics.

What, then, is this everyday use of ‘logic”? Does it just fall back to the realms of natural language and the rules governing that?

This would appear too broad, since almost anything that is comprehensible becomes logical. And this simply won”t do. Because a universe where anything goes, nothing can be properly considered ‘logical”.

But we have one requirement or feature of the everyday notion of logic: ‘must make sense”6.

What next? How can we narrow this down? Well, we often see that fallacies are talked about an awful lot. And this gives us at least one more feature: must not use a fallacy

What else? Hrm… this is actually getting tougher.

Well, we could cheat and take a peek at what I said in footnote #6. Where I mention the following sound and valid instance of modus ponens:

  1. If 3 is a prime number then humans are mammals
  2. 3 is a prime number
  3. Therefore humans are mammals

This argument, yes, is comprehensible but it seems… idk. Not quite right. One way we could say that this ‘feels” wrong, or seems counter-intuitive, is the fact that ‘3 is prime number” appears to have no real world relation to ‘humans are mammals”. So, we could maybe say that this fails on grounds of relevance.

How about we make this a third requirement: there must be some sort of relevant relationship between the elements of an argument.

(Um… I wrote this ages ago and I can”t really remember why or where I was going with it all….)