Comments on “Logic as eternalism”



Sasha's picture

Logic is “discredited and abandoned”??
That’s news to me. How does one even reason or think without logic? How would algorithms and computer programs operate without logic? Etc. Please explain (without using logic, of course).

Logic is discredited

Sean Seefried's picture

David, I’d very much like to see you expand this section as I don’t think the notion that logic has been discredited is very well known at all. It could just be the circles I travel in that make me feel that. I’m a CS major.

Logic as theory vs. logic as tool

James's picture

I’m not David, but I’m pretty sure I know what he’s going for with this: the page says, “Logic was the main theory of rationality for thousands of years.” Logic is thus discredited as a theory of rationality. It’s not discredited as a tool of rational thought.

A similar confusion exists with the term “empiricism”: I’ve mentioned before in an online conversation that I consider empiricism to be a failed theory of knowledge and was told that I had to be crazy to reject the use of empirical data in reasoning. But that’s not what I meant at all: what I meant was that the schools of philosophy collectively called “empiricism” all suffered common flaws (among others, Quine’s Two Dogmas and Davidson’s Third Dogma) that rendered them all either wrong or trivial.

Logic as a tool of rationality not a theory of rationality

Sean Seefried's picture

James, thank you very much for your reply. I think what I need now is a primary source that describes the problems of using logic as a theory of rationality, and perhaps some sources to modern theories of rationality.

The decline and fall of logic

Part I of In The Cells Of The Eggplant is mostly about how logic doesn’t work as a theory of rationality. (The rest of that Part is about how probability theory doesn’t work either.)

Coincidentally, I posted one relevant section of it, “The Spanish Inquisition,” a few days ago. That explains one of the dozen or so reasons logic can’t work as a theory of rationality. (Another dozen sections of the book will explain others of those reasons.)

As James explains, logic can be a powerfully useful tool, in restricted circumstances, but that’s a very different thing from being a theory of rationality.

There have been two main episodes of logical eternalism, Logical Positivism (early 20th century to early 1960s), and AI logicism (late 1950s to about 1990). I don’t know of any good history of either, or concise explanation for why they failed. (The Eggplant aims to supply the latter but mostly not the former.) If you don’t want to wait for it, and really want to know the story, you could read up on those two movements.

This apparently silly post is more serious than it appears, and following the links would be a good start for understanding the failure of AI logicism.

There aren’t any serious modern theories of rationality. Since the failure of logical positivism, no theory has even attempted to address the difficult issues that LP failed on. Subsequent theories have been non-serious in the sense that they aren’t even trying.

Logic as a theory of rationality

James's picture

David and Sean,

There was also the assumption that all thought - even perception - is a matter of performing unconscious syllogisms. That seems obviously silly now, but as I understand it seemed just as obviously correct to scholars of medieval Europe and the Middle East.

It strikes me as very much like how contemporary rationalists tend to view the brain as basically a Bayesian update machine.

Logic and the Psychology of Reasoning

Ah, by chance, I was just now reminded of a good brief survey article that sketches the history and evidence: Catarina Dutilh Novaes, “Logic and the Psychology of Reasoning.”

From it:

Currently, the consensus among psychologists of reasoning is that classical, deductive logic is not at all an adequate descriptive model for human reasoning. The shift from these earlier views to the current status quo has been described as an authentic Kuhnian paradigm shift in the psychology of reasoning (Elqayam 2018). But this conclusion gives rise to a host of new questions, such as: if traditional logic is not an adequate description of human reasoning, is there an alternative theoretical framework that is more descriptively adequate? Some prominent candidates are Bayesian probability calculus (Oaksford & Chater 1991) and non-monotonic logics (Stenning & van Lambalgen 2008). Another crucial question is whether traditional logic remains normatively adequate despite these descriptive discrepancies, which would mean that humans make systematic and frequent mistakes when reasoning. However, it has been argued that deductive logic is also thoroughly inadequate even as a normative model for reasoning (Harman 1986, Dutilh Novaes 2015). But then, what is logic actually about, if it is neither descriptively nor normatively adequate as an account of human reasoning?

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This page is in the section Rationalist ideologies as eternalism,
      which is in Non-theistic eternalism,
      which is in Eternalism: the fixation of meaning,
      which is in Meaning and meaninglessness,
      which is in Doing meaning better.

The next page in this section is ⚒︎ The continuum gambit.

The previous page is ⚒︎ Eternalisms as wrong-way reductions.

This page’s topics are Eternalism and Rationalism.

General explanation: Meaningness is a hypertext book (in progress), plus a “metablog” that comments on it. The book begins with an appetizer. Alternatively, you might like to look at its table of contents, or some other starting points. Classification of pages by topics supplements the book and metablog structures. Terms with dotted underlining (example: meaningness) show a definition if you click on them. Pages marked with ⚒ are still under construction. Copyright ©2010–2020 David Chapman. Some links are part of Amazon Affiliate Program.