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The metaphysical presuppositions of formal logic

edwardfeser.blogspot.com

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Re: The metaphysical presuppositions of formal logic

#11

Post by ukj »

voxl wrote: post #10
ukj wrote: post #2

This article does a great deal to point out the problem, but then just kicks the can down the road. Yes, metaphysics comes before Logic but metametaphysics comes before metaphysics. Ad infinitum. All this does is shift the discussion from the laws of logic to the laws of metaphysics - it is turtles all the way down. There is no way to get off this hamster wheel without a shift of perspective, but computer scientists…

Its not turtles all the way down, because there is a preexisting substrate that allows the discussion to happen in the first place. It is not a presupposition, because to merely state the _possibility_ of it being a presupposition necessitates its existence. There has to be some kind of preexisting substrate that enables thought. A recursive function can't run without a machine to run it.

You mean like the entity which invents/designs/defines the concepts of "substrate", "possibility","necessity" and "existence" ?

The entity which measures and then captures regularities in "the substrate" in the forms of Mathematical equations (formal languages) - that which we call "laws of physics"? Even though physicists haven't yet solved the measurement problem.

The entity that is trying to understand what it is made of and how it works? The entity that is trying to define itself?

The function is running, alright and it's trying to reverse-engineer its runtime. The question is whether the function is recursive.

Most functions refer to themselves as "I".

Re: The metaphysical presuppositions of formal logic

#12

Post by momentoftop »

xondono wrote: post #7

IMO This article is a mess. Starts with an interesting premise, the foundations of logic (or rather, what people are taught as the foundations of logic) introduces unspoken assumptions. Then it goes on to illustrate with the worst example I can think off. modern physics’ mathematical representations [...] tend to insinuate an eternalist rather than presentist conception of time. I don't know which modern physicists h…

"Eternalism" refers to the static "block universe" conception of spacetime, where all events exist simultaneously, past, present and future. "Presentists", by contrast, hold that the past no longer exists, the future does not yet exist and only the present moment exists. Neither are positions about whether there is/was a first moment of time.

I just finished reading the physicist Sean Carroll's book "From Eternity to Here", which is mostly about the thermodynamic arrow of time and big bang cosmology. He briefly discusses presentism and eternalism, before writing:

"Concerning the debate between eternalism and presentism, a typical physicist would say: 'who cares?'"

To be fair to Feser, I don't think he's commenting on the attitudes of contemporary physicists, but on a particular presentation of physics and logic. I doubt any working physicist cares one jot about this presentation, or formal predicate logic in general. Philosophers may well care, and Feser might just be noticing that his colleagues take formal logic far more seriously than it deserves.

Re: The metaphysical presuppositions of formal logic

#13

Post by practal »

momentoftop wrote: post #12
xondono wrote: post #7

IMO This article is a mess. Starts with an interesting premise, the foundations of logic (or rather, what people are taught as the foundations of logic) introduces unspoken assumptions. Then it goes on to illustrate with the worst example I can think off. modern physics’ mathematical representations [...] tend to insinuate an eternalist rather than presentist conception of time. I don't know which modern physicists h…

"Eternalism" refers to the static "block universe" conception of spacetime, where all events exist simultaneously, past, present and future. "Presentists", by contrast, hold that the past no longer exists, the future does not yet exist and only the present moment exists. Neither are positions about whether there is/was a first moment of time. I just finished reading the physicist Sean Carroll's book "From Eternity to…

Very rarely, physists DO care about logic.

For example: https://www.jstor.org/stable/1968621 And: https://en.wikipedia.org/wiki/The_Logic_of_Modern_Physics

But given that the first is from 1936 and the second from 1927, maybe that's out of fashion.

Re: The metaphysical presuppositions of formal logic

#14

Post by practal »

ukj wrote: post #9
continuational wrote: post #6

This seems too vague to me, like a lot of philosophical posts out there. > For example, if it is true that Aunt May believes that Spider-Man fights crime, then even though Spider-Man = Peter Parker, it does not follow that Aunt May believes that Peter Parker fights crime. If you can't substitute Peter Parker for Spider-Man, then they are by definition not equal...

There are different kinds of "equality", beyond the one you are invoking: https://ncatlab.org/nlab/show/equality#DifferentKinds The most obvious example of A != A being true I can think of is the evaluation of this expression in any programming language: Time.now == Time.now

Good example why programming and logic are related, but not the same.

Re: The metaphysical presuppositions of formal logic

#15

Post by ukj »

practal wrote: post #14
ukj wrote: post #9

Earlier quoted context omitted.

There are different kinds of "equality", beyond the one you are invoking: https://ncatlab.org/nlab/show/equality#DifferentKinds The most obvious example of A != A being true I can think of is the evaluation of this expression in any programming language: Time.now == Time.now

Good example why programming and logic are related, but not the same.

Yes well..

Any two objects are the same, except for their differences. Any two objects are different, except for their similarities.

"Sameness" and "difference" are abstract assertions. So in saying that you are doing programming; or maybe I am doing fuzzy logic.

From my perspective it seems like you are evaluating this expression:

  same?(Logic, Programming) -> False
But a different Oracle machine might produce a different answer :)

Re: The metaphysical presuppositions of formal logic

#16

Post by tgv »

continuational wrote: post #6

This seems too vague to me, like a lot of philosophical posts out there. > For example, if it is true that Aunt May believes that Spider-Man fights crime, then even though Spider-Man = Peter Parker, it does not follow that Aunt May believes that Peter Parker fights crime. If you can't substitute Peter Parker for Spider-Man, then they are by definition not equal...

In this case, that doesn't matter. What matters is if Aunt May knows or believes that Peter Parker is Spider Man. The equation "Spider-Man = Peter Parker" may be true in the example, but that doesn't mean much. Imagine that we could only think true thoughts...

Re: The metaphysical presuppositions of formal logic

#17

Post by xondono »

momentoftop wrote: post #12
xondono wrote: post #7

IMO This article is a mess. Starts with an interesting premise, the foundations of logic (or rather, what people are taught as the foundations of logic) introduces unspoken assumptions. Then it goes on to illustrate with the worst example I can think off. modern physics’ mathematical representations [...] tend to insinuate an eternalist rather than presentist conception of time. I don't know which modern physicists h…

"Eternalism" refers to the static "block universe" conception of spacetime, where all events exist simultaneously, past, present and future. "Presentists", by contrast, hold that the past no longer exists, the future does not yet exist and only the present moment exists. Neither are positions about whether there is/was a first moment of time. I just finished reading the physicist Sean Carroll's book "From Eternity to…

Point taken, did not know about those technicalities, but I would argue that then, the example makes even less sense.

> "Concerning the debate between eternalism and presentism, a typical physicist would say: 'who cares?'"

This is a great illustration that physics doesn’t care one way or another, or more properly, from the point of view of physics the question is meaningless.

Claiming that somehow physics has a biased view in a question it refuses to address altogether is weird.

Re: The metaphysical presuppositions of formal logic

#18

Post by joshuak »

ukj wrote: post #9
continuational wrote: post #6

This seems too vague to me, like a lot of philosophical posts out there. > For example, if it is true that Aunt May believes that Spider-Man fights crime, then even though Spider-Man = Peter Parker, it does not follow that Aunt May believes that Peter Parker fights crime. If you can't substitute Peter Parker for Spider-Man, then they are by definition not equal...

There are different kinds of "equality", beyond the one you are invoking: https://ncatlab.org/nlab/show/equality#DifferentKinds The most obvious example of A != A being true I can think of is the evaluation of this expression in any programming language: Time.now == Time.now

These are imperative commands to execute, as apposed to a declarative statement comparing a value to itself.

You can’t switch between symbolic representations to use the meaning of one to make statements about the other because the meaning of the symbols also switch.

Re: The metaphysical presuppositions of formal logic

#19

Post by ukj »

joshuak wrote: post #18
ukj wrote: post #9

Earlier quoted context omitted.

There are different kinds of "equality", beyond the one you are invoking: https://ncatlab.org/nlab/show/equality#DifferentKinds The most obvious example of A != A being true I can think of is the evaluation of this expression in any programming language: Time.now == Time.now

These are imperative commands to execute, as apposed to a declarative statement comparing a value to itself. You can’t switch between symbolic representations to use the meaning of one to make statements about the other because the meaning of the symbols also switch.

So you are telling me that I can't choose to declare that A = A is false?

Telling me what I can and can't do is an imperative statement...

Re: The metaphysical presuppositions of formal logic

#20

Post by joshuak »

ukj wrote: post #19
joshuak wrote: post #18

Earlier quoted context omitted.

These are imperative commands to execute, as apposed to a declarative statement comparing a value to itself. You can’t switch between symbolic representations to use the meaning of one to make statements about the other because the meaning of the symbols also switch.

So you are telling me that I can't choose to declare that A = A is false? Telling me what I can and can't do is an imperative statement...

You certainly may define your own symbology.

But if you want to communicate with others you’ll need to agree on your symbology.

In the common mathematical understanding A != A is defined as a false statement. In any example that one can contemplate it would become a true statement then you are replacing one of the ‘A’ symbols with something that is not ‘A’ in your mind.

Which is to say you are using the wrong symbols to represent the idea you intend to communicate.

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