On Logic, and How Not to Do It (1913) | Hacker News Reader

On Logic, and How Not to Do It (1913)

landondcelkind.com

61 pointshrl12 comments

I wonder if Coffey's logic book was worse than most of the time. I have not read it, but it's available: https://archive.org/details/thescienceoflogi01coffuoft

I have strong feelings about the usefulness of this sort of logic despite its flaws, and would have been interested to know his thoughts on W.S. Jevons' book.

That sort of logic is of really limited usefulness. It does not even allow, strictly speaking, to take "Horse is an animal" and derive "a horse's head is an animal's head". That's is why mathematicians tended to disregard logic as useless for the maths up until the late XIX century when they actually bothered to invent the mathematical logic -- that's when the modern delusion that "logic is a part of mathematics" apparently is originated. It's not, it's still a part of (mostly scholastic) philosophy.

Russell has a rather nice sum of problems with Aristotle's logic in his "History of Western Philosophy", actually.

It is useless in any situation in which absolute rigor is required, but its close relation to human language makes it excellent for developing logical habits of thought in practical situations. Proper mathematical logic fixes its biggest problems, and is incredibly useful in its own way --- I don't mean to dismiss it in any way --- but as a tool for developing non-mathematician non-philosopher people's rational capabilities, I still hold it's unmatched because of its verbal, intuitive character.

This "verbal, intuitive character" is its biggest flaw: it makes grammar look like it is logic, while it is not. That's how you get "cogito ergo sum" instead of "cogitationes sunt", or the ontological argument.

I think you're agreeing with me in that term logic is inappropriate for rigorous uses, though your examples are not really the results of its admitted flaws.

Let me clarify the area where I believe it is useful: the study of term logic helps prepare the minds of non-philosophers to reason, speak, and write clearly about concrete but often ill-defined matters of everyday life. While it lacks rigor, it forces them to consider the implications of their words and those of others, and how those words operate to express proof and disproof. The study of symbolic and other more formal systems of logic, while essential for more rigorous reasoning, requires too much time and application to achieve similar results, because their mode of expression is too removed from the experience of non-philosophers and especially non-mathematicians.

> This "verbal, intuitive character" is its biggest flaw: it makes grammar look like it is logic, while it is not.

I don't know if I would say it makes grammar look like logic. Rather, it holds that grammar has a logical structure. You would still need to regiment your arguments in many cases if you wanted to explicitly employ the formalism in question, but this is viewed as faithfully bringing out the essential logical character of a proposition latent in the grammar, not as a replacement of the original proposition with something else. Recall that FOL is completely indifferent to grammar (though apparently this hasn't stopped linguists from using FOL to analyze natural language, something Sommers sees as resulting in a distorted view of natural language).

You express strong views about mathematical logic (i.e. first-order logic) as part of mathematics, but do you disregard the contributions of first-order logic to the theory of computation, or do you consider the theory of computation to be part of philosophy rather than mathematics?

This was Wittgenstein's first publication, I believe, and it shows. As someone once wrote, not Wittgenstein's finest hour.

> It does not even allow, strictly speaking, to take "Horse is an animal" and derive "a horse's head is an animal's head".

This is because it doesn't permit relations in a systematic way. In FOL, you would express "head of" as binary relations (one for horse, one for animal since you cannot quantify over predicates; you would need a HOL for that). But traditional logic can be extended with relations as Sommers has done in term functor logic.

Interestingly, Veatch argues that FOL cannot tell you what a thing is. If predicates are modeled after relations—and Russell also includes the unary predicate here as a relation between subject and property instead of multiple subjects—then you cannot say what a thing is because relations don't say what their relata are. So you're left with a peculiar situation where individuals are bare particulars which brings up all sorts of other questions.

Sommers and Englebretsen have interesting things to say in response to Russell and Frege as well as their defenders (like Geach and Dummett).

I find it a little strange to put the date 1913 on this title, when it’s actually a fairly recent article, about something from 1913.

You confound complexes and sums. (The preamble and the article comprises the web page, but the web page is not a complex of the article and itself.)

I might be too dumb to understand what you are saying. But, is it in the lines of: "it can be considered that the actual information is the digitised text from 1913, which is arguably more important than the digitisation of it, and when"?

If so, I agree.

I think the poster is using the content of the article to make a joke.

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