Philosophical Vegan Forum

brimstoneSalad wrote:Notions of platonic ideals for things like "dogs" are incoherent, but that doesn't mean there isn't any concept with an ideal.

How do you deduce which ideals are Platonizible?

Cirion Spellbinder wrote: ↑Fri May 11, 2018 3:41 pm

brimstoneSalad wrote:Notions of platonic ideals for things like "dogs" are incoherent, but that doesn't mean there isn't any concept with an ideal.

How do you deduce which ideals are Platonizible?

I would say anything we can pretty clearly examine the teleology of can have an ideal.

Math, Morality, Thermodynamics (ideally efficient engines of varying kinds).

So, if we define an ecological niche, we could talk about the ideal creature to fill it, but the function of a "dog" is multi-faceted. A dog does a lot of things; it evolved to fill a niche, but then was adopted by humans for several other purposes which can be at odds with each other, and as well is a sentient being with some general notion as to its own interests and ideals.

@brimstoneSalad

brimstoneSalad wrote: ↑Fri May 11, 2018 2:44 pm "Tomorrow will be a sea battle" is simply false as a SET of claims because it's loaded with incorrect metaphysical claims about determinism. It has nothing to do with the "sea battle" part and it doesn't mean that tomorrow will not be a sea battle.

The claim "Tomorrow will be a sea battle" is also the claim that there is a single universe in which future claims are absolute (loaded into "tomorrow will be"), which is the part that is false, so "tomorrow will not be a sea battle" is no more true.

It's a SET of statements.

Like this: Santa wears pants. This is a set of implicit statements: {Santa exists. He wears Pants. and more...}
Saying that is false in a logical sense as a SET which contains at least ONE false claim is not a claim of negation for any arbitrary one of the premises while leaving the others in-tact. "Santa wears pants" being false should not imply that Santa exists but doesn't wear pants, it could also mean that Santa does not exist but does wear pants (in the stories), or that he does neither of those things.

The bottom line is lack of precision: you need to break down your claims into EVERYTHING they're suggesting, then those claims can be evaluated one by one. If you evaluate them as a set you have to say it's false if it contains one false claim, and then due to ambiguity in English that falsehood may be incorrectly attributed to a specific part of the claim.

English semantics are loaded with many implicit premises. If any ONE of those is false, then the set is not true.

Does that answer the question better?

Obviously you can form any number of incoherent statements in English, like "this sentence is a lie"; that doesn't invalidate classical logic, it shows that English is not rigorously consistent or metaphysically accurate.

That's between the lines of what I meant by that the classical logic collapses in the view of quantum mechanics (QM). Until QM one could speculate more freely on metaphysics to see which statements are coherent, and which are not, with the most popular interpretation of QM it's just more... suggestive.
That said, if you come to the conclusion that such simple statements are incoherent in the view of classical logic, it means exactly what I try to convey - that classic logic isn't that great to model the natural language. The moment you invoke some universes is the moment you dropped classical logic as the model for the natural language and brought modal logic as your model of choice. Yes, we handle modal logic with tools and notions from the classical logic, but clearly you don't use only classical logic anymore to evaluate statements about the reality. Or in other words - the statement about a sea battle, or the one on the spin of the electrone, are incoherent in the classical logic, but perfectly sensible in the modal logic, and you proved it yourself. The answer in the classical logic to both of them is "whaaaat?", but using modal logic you may answer "maybe", and it's legitimate answer, but you lacked that possibility in the classical logic, so you blamed me for being imprecise by asking about truth values of one of the most common types of statements in the natural language.

Hope I'm precise enough now

brimstoneSalad wrote: ↑Fri May 11, 2018 2:44 pm Now I think you're just begging the question.

And why is that?

@Cirion Spellbinder

Cirion Spellbinder wrote: ↑Fri May 11, 2018 3:38 pm The rest of what I've said to you I can research on my own, like you've pointed it out, since you hate me so

It will be much better for you. For many of these things we discuss here one need some time to process it, and asking a lot of similar questions won't help you that much.

Cirion Spellbinder wrote: ↑Fri May 11, 2018 3:38 pm I'm willing to make practical concessions to be able to reason about the real world. Induction is sketchy, but we don't have a full picture yet.

Of course.

Cirion Spellbinder wrote: ↑Fri May 11, 2018 3:38 pm What does it mean that formulas must be finite?

Consists of finitely many letters of the language. If you don't think that formulas should be finite, try to formulate an infinite formula. I'll wait

Cirion Spellbinder wrote: ↑Fri May 11, 2018 3:38 pm I've already acknowledged that the first premises are arbitrary, but it is rational to minimize arbitrariness if I want to be able to have meaningful views and maximize coherence.

I would just say for the sake of any discussion all participants should agree on definitions and premises, and then proceed without adding new arbitrary rules.

Cirion Spellbinder wrote: ↑Fri May 11, 2018 3:38 pm Do you agree that introducing more arbitrary things detracts from order? Given that you can see the flaws of induction, I'd have to image you'd prefer an ordered world. If you act rationally with this interest, you will attempt to minimize the amount of assumptions you need to make to the greatest extent to which you are still able to describe reality. If you don't care about being able to understand as efficiently as you can, then sure, make arbitrary assumptions which will not help you in any way, but you can't say that you want to have meaningful opinions on anything (unless we have supposed it as a premise ).

What's order in this context? I make some arbitrary assumptions, but don't stick to them beyond their usefulness. For induction principle it's the same. It allows you treat repeated observations like they express some truth about the reality (or confirm the theory in which you operate), but you must also be ready to defend the paradigms of the teory against experiments that apparently disprove the theory, by looking for errors in the set up of these experiments and so on. It's vague, but it doesn't make your actions meaningless.

mkm wrote: ↑Sat May 12, 2018 6:44 amUntil QM one could speculate more freely on metaphysics to see which statements are coherent, and which are not,

Sure, but now we just know more about which metaphysics are invalid. That does nothing to classical logic, which isn't committed to any invalid metaphysics.

mkm wrote: ↑Sat May 12, 2018 6:44 amThat said, if you come to the conclusion that such simple statements are incoherent in the view of classical logic, it means exactly what I try to convey - that classic logic isn't that great to model the natural language.

More specifically that natural language can model statements that are inconsistent and incoherent. This isn't a flaw of classical logic, it's a flaw of the user of language for lacking precision.

mkm wrote: ↑Sat May 12, 2018 6:44 amThe moment you invoke some universes is the moment you dropped classical logic as the model for the natural language and brought modal logic as your model of choice.

What? No. It was the moment I introduced metaphysical premises to deal with the metaphysical implications in the statement.

Modal logic can be useful since it's not making any specific metaphysical commitments, but failing to make those metaphysical commitments means it doesn't necessarily map to reality (even if it may represent the ambiguity of natural language better, that doesn't mean anything).
If you introduce those necessary premises, however, modal logic can be circumvented and we know (as long as those premises are true) that it's going to map well to reality.

mkm wrote: ↑Sat May 12, 2018 6:44 amYes, we handle modal logic with tools and notions from the classical logic, but clearly you don't use only classical logic anymore to evaluate statements about the reality.

You can add on more axioms if you want to, in order to deal with these things, or you can handle it by making some metaphysical commitments.
My point is only that your claim that classical logic is inherently inadequate isn't true.

mkm wrote: ↑Sat May 12, 2018 6:44 amOr in other words - the statement about a sea battle, or the one on the spin of the electrone, are incoherent in the classical logic, but perfectly sensible in the modal logic, and you proved it yourself.

Or they're just naturally incoherent, and you have to bootstrap on some extra ad hoc axioms which you can't substantiate without making the very metaphysical commitments that if used in classical logic can make those statements coherent.

Not seeing the benefit here.

Modal logic was even developed after the inception of MWI, so it was technically never needed to make sense of QM... although of course I understand that information probably moves slowly from cutting edge theoretical physics to philosophy (MWI is only just gaining significant ground among physicists).

mkm wrote: ↑Sat May 12, 2018 6:44 amThe answer in the classical logic to both of them is "whaaaat?", but using modal logic you may answer "maybe", and it's legitimate answer

And what substantiates the extra axioms you must assume to legitimize it?
Hmm...

The same substantiation applied as a premise in classical logic can carry the same load. Occam's razor would prefer classical logic since it CAN do the same thing if you just include the relevant metaphysical premises. You need fewer axioms.

Now if you just want something cleaner to work with that's fine, but you can't claim it's superior. That's like using Newtonian physics to solve your problem within a certain margin of error; that's perfectly acceptable, but you're missing something.

mkm wrote: ↑Sat May 12, 2018 6:44 amIt will be much better for you. For many of these things we discuss here one need some time to process it, and asking a lot of similar questions won't help you that much.

Do you recommend any resources?

mkm wrote:Consists of finitely many letters of the language. If you don't think that formulas should be finite, try to formulate an infinite formula. I'll wait

Can it explain an infinite number of steps using finite words, like the golden ratio or rational repeating decimals?

mkm wrote:I would just say for the sake of any discussion all participants should agree on definitions and premises, and then proceed without adding new arbitrary rules.

Agreed, but to have a meaningful discussion about reality do you think it would be worthwhile to arbitrarily select those premises and definitions or only give half the effort into selecting them carefully?

mkm wrote:What's order in this context?

Coherence, mostly. Basically that what we discuss will always be understandable by having no contradictions and if we had the full picture, would allow for all true statements to be deduced.

mkm wrote:I make some arbitrary assumptions, but don't stick to them beyond their usefulness.

Agreed.

mkm wrote:For induction principle it's the same. It allows you treat repeated observations like they express some truth about the reality (or confirm the theory in which you operate), but you must also be ready to defend the paradigms of the teory against experiments that apparently disprove the theory, by looking for errors in the set up of these experiments and so on. It's vague, but it doesn't make your actions meaningless.

Experiments rely on induction as well, just meaning that induction in a controlled environment will probably be stronger than in an uncontrolled one. I'm not sure how that is vague outside of induction itself.

@brimstoneSalad

brimstoneSalad wrote: ↑Sat May 12, 2018 2:41 pm Sure, but now we just know more about which metaphysics are invalid. That does nothing to classical logic, which isn't committed to any invalid metaphysics.

I would be very careful with such statements. In the case of QM it's not that determinism is invalid, but the most popular interpretation (which is metaphysical anyway) invalidates it. What physicist really do here is they pick more elegant interpretation.
The classical logic is not committed to any metaphysics, it's just a formal system. It's interpretation when we try to model statements about the reality in natural language is.

brimstoneSalad wrote: ↑Sat May 12, 2018 2:41 pm What? No. It was the moment I introduced metaphysical premises to deal with the metaphysical implications in the statement.

Yes, you said "the claim "Tomorrow will be a sea battle" is also the claim that there is a single universe in (...)", at least that's what I'm referring to. To make sense of the statement about the sea battle you switch to modal logic.

brimstoneSalad wrote: ↑Sat May 12, 2018 2:41 pm Modal logic can be useful since it's not making any specific metaphysical commitments, but failing to make those metaphysical commitments means it doesn't necessarily map to reality (even if it may represent the ambiguity of natural language better, that doesn't mean anything).
If you introduce those necessary premises, however, modal logic can be circumvented and we know (as long as those premises are true) that it's going to map well to reality.

By introducing those premises (universes and such) you already model statements in the natural language on the reality by modal logic. Explicitly. You think you are circumventing it, but you don't.

brimstoneSalad wrote: ↑Sat May 12, 2018 2:41 pm You can add on more axioms if you want to, in order to deal with these things, or you can handle it by making some metaphysical commitments.

I fail to see how these two differ significantly, if they result in essentailly the same thing.

brimstoneSalad wrote: ↑Sat May 12, 2018 2:41 pm My point is only that your claim that classical logic is inherently inadequate isn't true.

It's not my claim.

brimstoneSalad wrote: ↑Sat May 12, 2018 2:41 pm Or they're just naturally incoherent, and you have to bootstrap on some extra ad hoc axioms which you can't substantiate without making the very metaphysical commitments that if used in classical logic can make those statements coherent.

Not seeing the benefit here.

What do you mean by naturally incoherent? In natural language as long as a statement is gramatically correct (i.e. it's a well formed formula), it's OK. It's interpretation in a certain logic may be incoherent, and then statement on the reality modelled by that logic may have no sense.

Ad the second part. I just notice, that for future contingents to work in the classical logic one has to accept logical determinism. You bring all these new assumptions, because you have it backwards - you assume indeterminism (suggested for example by the common interpretation of QM, or for no apparent reason) then break down the statement with respect to your metaphysical assumptions, and declare it's incoherent. And you do this de facto via modal logic (explicitly using possible universes), although you don't want to admit it for some reason. Or I don't undestand something.

brimstoneSalad wrote: ↑Sat May 12, 2018 2:41 pm Modal logic was even developed after the inception of MWI, so it was technically never needed to make sense of QM... although of course I understand that information probably moves slowly from cutting edge theoretical physics to philosophy (MWI is only just gaining significant ground among physicists).

Not really, modal logic dates to 30' of the last century and MWI was introduced in 50' I believe (quick search through Internets, don't blame me ).

brimstoneSalad wrote: ↑Sat May 12, 2018 2:41 pm And what substantiates the extra axioms you must assume to legitimize it?
Hmm...

The same substantiation applied as a premise in classical logic can carry the same load. Occam's razor would prefer classical logic since it CAN do the same thing if you just include the relevant metaphysical premises. You need fewer axioms.

Again, I fail to see they differ. Why do you think making metaphysical premises trumps introducing different model of underlying logic? Especially if you can transfer one into another, while you metaphysical premises reformulate the original statement? Why would Occam's razor prefer mataphysical assumptions over axioms of logic?

brimstoneSalad wrote: ↑Sat May 12, 2018 2:41 pm Now if you just want something cleaner to work with that's fine, but you can't claim it's superior. That's like using Newtonian physics to solve your problem within a certain margin of error; that's perfectly acceptable, but you're missing something.

I think it's the other way around. Modal logic is like the Copernican model, and the classical logic is like the model of Ptolemeus - you can patch the holes with additional metaphysical premises (epicycles), or come up with different model (with circular orbits).
What am I missing?

@Cirion Spellbinder

Cirion Spellbinder wrote: ↑Sat May 12, 2018 3:38 pm Do you recommend any resources?

Starting from scratch, I would advice going through some basic course of the set theory (there is a bible "Set Theory" by Thomas Jech, though it's a dense read) mathematical logic ("Introduction to mathematical logic" by Enderton comes to mind) to get familiar with concepts. Some background in algebra and topology woudln't hurt, since some notions are very similar and it's easier to understand with wider view. Then feel free to choose any introduction to the modal logic. There is a free book by Goldblatt "Logic of time and computation" for example.

Cirion Spellbinder wrote: ↑Sat May 12, 2018 3:38 pm Can it explain an infinite number of steps using finite words, like the golden ratio or rational repeating decimals?

We have induction for this. For "golden ratio" you define Fibonacci sequence of F(n) and take the limit of F(n+1)/F(n).

Cirion Spellbinder wrote: ↑Sat May 12, 2018 3:38 pm Agreed, but to have a meaningful discussion about reality do you think it would be worthwhile to arbitrarily select those premises and definitions or only give half the effort into selecting them carefully?

I don't know. Almost every back and forth in (honest) discussions boils down to different assumptions tacitly made by each party, so maybe we should be very careful.

Cirion Spellbinder wrote: ↑Sat May 12, 2018 3:38 pm Coherence, mostly. Basically that what we discuss will always be understandable by having no contradictions and if we had the full picture, would allow for all true statements to be deduced.

The problem is usually with the full picture though, so we have to speculate.

Cirion Spellbinder wrote: ↑Sat May 12, 2018 3:38 pm Experiments rely on induction as well, just meaning that induction in a controlled environment will probably be stronger than in an uncontrolled one. I'm not sure how that is vague outside of induction itself.

Vague in the sense it seems paradoxical relying on induction, but defending paradigms of the theory at the same time. There are no clear criterions when the theory really collapses, or just needs to be refined. Sometimes theories are accepted beside the fact that there are experimental disproofs of the theory (it was the case for Copernican theory).

mkm wrote: ↑Sun May 13, 2018 6:25 am It's not my claim.

Didn't you say it couldn't deal with QM?

mkm wrote: ↑Sun May 13, 2018 6:25 am What do you mean by naturally incoherent? In natural language as long as a statement is gramatically correct (i.e. it's a well formed formula), it's OK. It's interpretation in a certain logic may be incoherent, and then statement on the reality modelled by that logic may have no sense.

I'm not talking about grammar.

What do you make of "This sentence is a lie"?

mkm wrote: ↑Sun May 13, 2018 6:25 am I just notice, that for future contingents to work in the classical logic one has to accept logical determinism.

In some sense, yes: but that is reality. Otherwise logic really has no point.

mkm wrote: ↑Sun May 13, 2018 6:25 am And you do this de facto via modal logic (explicitly using possible universes), although you don't want to admit it for some reason. Or I don't undestand something.

You don't understand something.

All of these possible universes are not "possible" in the colloquial sense in that they only might happen, they are all real and actualized independently.
I thought you knew what MWI was about.
They are "possible" in terms of a physical configuration that is not in violation of logic. We can say "all consistent universes" if you want. I'm not using modal logic.

mkm wrote: ↑Sun May 13, 2018 6:25 am Why would Occam's razor prefer mataphysical assumptions over axioms of logic?

Metaphysics is empirically accessible on some level, it is presented as a premise to be challenged. New axioms are only asserted and assumed; you should do as little of the latter as possible.

mkm wrote: ↑Sun May 13, 2018 6:25 am you can patch the holes with additional metaphysical premises (epicycles), or come up with different model (with circular orbits).
What am I missing?

I don't see it as hole patching. Metaphysics belongs in the premises where it can be challenged and discussed, unquestionable axioms are the last resort when you can't figure out any other way to make sense of something. We don't need to be patching on more ad hoc axioms to logic itself.

mkm wrote: ↑Sun May 13, 2018 6:25 am

brimstoneSalad wrote: ↑Sat May 12, 2018 2:41 pm What? No. It was the moment I introduced metaphysical premises to deal with the metaphysical implications in the statement.

Yes, you said "the claim "Tomorrow will be a sea battle" is also the claim that there is a single universe in (...)", at least that's what I'm referring to. To make sense of the statement about the sea battle you switch to modal logic.

How? I'm just demonstrating the hidden assumptions there which are not true.
Modal logic doesn't answer the questions about what probability metaphysically is: that's its benefit, but also a serious limitation because it's just question begging if you try to relate it back to reality. In so answering those metaphysical questions by clarifying the premises, that issue can be avoided.

mkm wrote: ↑Sun May 13, 2018 6:25 amBy introducing those premises (universes and such) you already model statements in the natural language on the reality by modal logic. Explicitly. You think you are circumventing it, but you don't.

All I'm doing is classical logic, if you think adding a simple metaphysical premise turns it into modal logic I don't know what to tell you. It's really not a modal premise, it's MWI.

Modal logic avoids making metaphysical commitments by moving the axioms OUT of the argument and just taking them for granted as part of the system: this is advantageous in that it makes discussion more streamlined and avoids getting people bogged down in arguments about metaphysics when they're not relevant to the points at hand.
However, asserting these things as axioms also fails to answer how they, or the results of the reasoning, are connected to reality. The axioms must be justified or they can not be preferred to the simpler set of axioms in classical logic.
Classical logic avoids taking on additional axioms (preferred by Occam's razor) and instead requires substantive metaphysical premises to deal meaningfully with certain claims. However, the drawback here is that we could find disagreement on those premises. It's also something that probably wouldn't have been possible until the 1960s and it requires a more significant understanding of physics to engage in even trivial arguments.

Each approach has practical advantages and disadvantages, much like Newtonian physics vs. Relativity when you're trying to compute something in physics. Sometimes if you just want to know how fast an apple is going when it hits the ground within a couple significant figures Newtonian physics is better even though it's less accurate because it's simpler in practice. This would be the use of modal logic. But when we're talking about the true nature of reality there's no question: Newtonian physics is just a shorthand, it's fundamentally wrong in its metaphysical implications. Likewise with modal logic, it's just begging the question with all of those extra axioms; they still need metaphysical foundation to call the results real.

mkm wrote:Starting from scratch, I would advice going through some basic course of the set theory (there is a bible "Set Theory" by Thomas Jech, though it's a dense read) mathematical logic ("Introduction to mathematical logic" by Enderton comes to mind) to get familiar with concepts. Some background in algebra and topology woudln't hurt, since some notions are very similar and it's easier to understand with wider view. Then feel free to choose any introduction to the modal logic. There is a free book by Goldblatt "Logic of time and computation" for example.

I am currently listening to "Problems with Philosophy" by Bertrand Russell. Once I finish that I'll choose one of these to read. Thanks!

mkm wrote:We have induction for this. For "golden ratio" you define Fibonacci sequence of F(n) and take the limit of F(n+1)/F(n).

Oh, okay, but why is the golden ratio in quotes? Did I use the phrase incorrectly?

mkm wrote:I don't know. Almost every back and forth in (honest) discussions boils down to different assumptions tacitly made by each party, so maybe we should be very careful.

About the assumptions we make? Definitely, and I think we would be in agreement on that?

mkm wrote:The problem is usually with the full picture though, so we have to speculate.

As little as we can.

mkm wrote:Vague in the sense it seems paradoxical relying on induction, but defending paradigms of the theory at the same time.

Sorry, but I'm confused by this sentence, it seems like it wasn't finished?

mkm wrote:There are no clear criterions when the theory really collapses, or just needs to be refined.

Induction or a given theory justified by induction?

mkm wrote:Sometimes theories are accepted beside the fact that there are experimental disproofs of the theory (it was the case for Copernican theory).

Do you mean the fact that epicycles don't exist?

@brimstoneSalad

brimstoneSalad wrote: ↑Sun May 13, 2018 6:28 pm Didn't you say it couldn't deal with QM?

If for you it's equivalent to "the classical logic is inherently inadequate", then OK. But I wouldn't phrase it that way.

brimstoneSalad wrote: ↑Sun May 13, 2018 6:28 pm I'm not talking about grammar.

If you reffer to natural language, you're not talking about logic either.

brimstoneSalad wrote: ↑Sun May 13, 2018 6:28 pm What do you make of "This sentence is a lie"?

Funny sentence in the natural language, and you can't really express it in the classical logic.

brimstoneSalad wrote: ↑Sun May 13, 2018 6:28 pm In some sense, yes: but that is reality. Otherwise logic really has no point.

That's just an opinion, not a fact.

brimstoneSalad wrote: ↑Sun May 13, 2018 6:28 pm You don't understand something.

brimstoneSalad wrote: ↑Sun May 13, 2018 6:28 pm All of these possible universes are not "possible" in the colloquial sense in that they only might happen, they are all real and actualized independently.
I thought you knew what MWI was about.
They are "possible" in terms of a physical configuration that is not in violation of logic. We can say "all consistent universes" if you want. I'm not using modal logic.

It doesn't matter whether these universes are "real", "actualized", or some other meaningless (physiacally) statement. it's just a way of talking about this and the way we talk about this doesn't change whether these universes actually exist or not. And then I'm just pointing out that this way of talking is "isomorphic" to modal logic, whether you like, or not.

brimstoneSalad wrote: ↑Sun May 13, 2018 6:28 pmMetaphysics is empirically accessible on some level, it is presented as a premise to be challenged.

That sounds paradoxical. Metaphysics by definition is beyond physics. Eventually even QM doesn't invalidate determinism, only our favourite way of thinking about it does.

brimstoneSalad wrote: ↑Sun May 13, 2018 6:28 pm New axioms are only asserted and assumed; you should do as little of the latter as possible.

I don't buy it. You may add or drop axioms anytime, or switch to other logic altogether. It's not carved in stone. Assuming "too many" metaphysical premises is economically as cumbersome as assuming "too many" axioms of logic.

brimstoneSalad wrote: ↑Sun May 13, 2018 6:28 pm I don't see it as hole patching. Metaphysics belongs in the premises where it can be challenged and discussed, unquestionable axioms are the last resort when you can't figure out any other way to make sense of something. We don't need to be patching on more ad hoc axioms to logic itself.

Axioms are only "unquestionable". You may not like messing with axioms of logic, but it doesn't mean that it's prohibited or wrong, whatever that would mean.

brimstoneSalad wrote: ↑Sat May 12, 2018 2:41 pm How? I'm just demonstrating the hidden assumptions there which are not true.

Yeah, because you have it backwards (or missunderstood me). I started at the point where future contingents make sense, and achieved incoherence with our thinking about QM (or about determinism in general). You took underlying premises behind QM and showed that future contingents don't really make sense. Same shit, different way

brimstoneSalad wrote: ↑Sat May 12, 2018 2:41 pm Modal logic doesn't answer the questions about what probability metaphysically is: that's its benefit, but also a serious limitation because it's just question begging if you try to relate it back to reality. In so answering those metaphysical questions by clarifying the premises, that issue can be avoided.

It doesn't, because it's not its job. It's "just" a formal structure to express things. Classical logic does none of these things either. Whichever logic you try to relate to the reality, you make a metaphysical premise "chosen logic models (some?) statements (made in natural language!) about the reality". You can't do this without possessing some meta-level notion on what these objects in logic "really" mean.

brimstoneSalad wrote: ↑Sat May 12, 2018 2:41 pm All I'm doing is classical logic, if you think adding a simple metaphysical premise turns it into modal logic I don't know what to tell you. It's really not a modal premise, it's MWI.

If you don't see that your way of dealing with this is indistinguishable from "I model these things with modal logic", or you see it, but refuse to admit, there is nothing I can do.

I'll stop here, since in the rest of your post you just repeat things I addressed above and there is no need for me to repeat it.

@Cirion Spellbinder

Cirion Spellbinder wrote: ↑Mon May 14, 2018 12:45 am I am currently listening to "Problems with Philosophy" by Bertrand Russell. Once I finish that I'll choose one of these to read. Thanks!

You're welcome. If you like "philosophy of knowledge" (or maybe without "", I overuse it), try "What is this thing called science" by Alan Chalmers. Great read too.

Cirion Spellbinder wrote: ↑Mon May 14, 2018 12:45 am Oh, okay, but why is the golden ratio in quotes? Did I use the phrase incorrectly?

See above, I overuse "" . I use this phrase so rarely, that I automatically put it in the "".

Cirion Spellbinder wrote: ↑Mon May 14, 2018 12:45 am About the assumptions we make? Definitely, and I think we would be in agreement on that?

I think so, we may just put accents differently, but I don't think we have some fundamental disagreement now.

Cirion Spellbinder wrote: ↑Mon May 14, 2018 12:45 am As little as we can.

Sure.

Cirion Spellbinder wrote: ↑Mon May 14, 2018 12:45 am Sorry, but I'm confused by this sentence, it seems like it wasn't finished?

My English may be lacking, but I think (?) that I expressed what I wanted to express. What's not clear?

Cirion Spellbinder wrote: ↑Mon May 14, 2018 12:45 am Induction or a given theory justified by induction?

What do you mean?

Cirion Spellbinder wrote: ↑Mon May 14, 2018 12:45 am Do you mean the fact that epicycles don't exist?

Better, the theory with epicycles was more adequate than Copernican with circular orbits. Furthermore, there were observations that contradicted implications of the Copernican theory.

mkm wrote: ↑Mon May 14, 2018 6:00 am It doesn't matter whether these universes are "real", "actualized",

It does, actually; it matters a great deal. If you don't understand why it matters if something is real or not, I don't know what to tell you.

mkm wrote: ↑Mon May 14, 2018 6:00 amAnd then I'm just pointing out that this way of talking is "isomorphic" to modal logic, whether you like, or not.

If you want to call it "isomorphic" because it serves a similar function, that's fine, but it isn't the same thing. A bird and a bat aren't the same thing because they both fly either.

mkm wrote: ↑Mon May 14, 2018 6:00 am That sounds paradoxical. Metaphysics by definition is beyond physics.

It's like the "God of the Gaps"
What is solidly in the domain of metaphysics today is the physics of tomorrow. It's also debatable at the fringes; like QM interpretations.
Axioms, on the other hand, can not be challenged.

mkm wrote: ↑Mon May 14, 2018 6:00 amEventually even QM doesn't invalidate determinism, only our favourite way of thinking about it does.

Which is the whole point of the metaphysical premises.
Unless you deny that MWI is deterministic, or deny its validity, you have no leg to stand on in criticizing classical logic to be incapable of dealing with modal statements because there's no reason to believe such statements represent reality.

What you're doing is like criticizing geometry for being incapable of dealing with square circles. Maybe it doesn't deal with those things because those things are invalid by their very nature? Maybe that's OK that it ignores nonsense like that.

mkm wrote: ↑Mon May 14, 2018 6:00 amI don't buy it. You may add or drop axioms anytime, or switch to other logic altogether. It's not carved in stone.

Which is what makes your arguments non-credible. You're throwing in axioms arbitrarily without substantiating them.
I explained how this is not acceptable to Occam's razor. I don't know how else to explain this.

@Cirion Spellbinder Is there anything that didn't make sense to you in my explanation?

mkm wrote: ↑Mon May 14, 2018 6:00 amAssuming "too many" metaphysical premises is economically as cumbersome as assuming "too many" axioms of logic.

I understand how you think it's subjectively cumbersome, and I explained how in practice even something inaccurate like Newtonian physics can have advantages. I'm not sure what else I can say. Adding axioms does not mean those axioms are essential to logic. I understand that they can work, but it doesn't mean they represent reality, which leaves the whole argument begging the question based on the additional axioms being asserted.

It's better to solve problems with premises than by re-writing logic.

If you have to deal with assessing something somebody is saying about a square circle, the solution isn't to add on a bunch of ad hoc rules to 2d geometry that aren't substantiated. Sometimes it's as simple as saying "square circles as 2d shapes don't exist, but here's a cylinder: it's a circle in one plane and a square in another." Geometry already deals with a sort of square circle as long as they're in different planes as part of a 3d shape. No need to rewrite geometry on account of somebody who doesn't understand that (which is basically what you're trying to do with logic here, for those who don't metaphysically understand probability).

mkm wrote: ↑Mon May 14, 2018 6:00 amAxioms are only "unquestionable". You may not like messing with axioms of logic, but it doesn't mean that it's prohibited or wrong, whatever that would mean.

Do you understand how it's a violation of Occam's razor to assert additional axioms when they're not necessary?

mkm wrote: ↑Mon May 14, 2018 6:00 amIt doesn't, because it's not its job. It's "just" a formal structure to express things.

I know.

mkm wrote: ↑Mon May 14, 2018 6:00 amClassical logic does none of these things either.

But you can do it within classical logic. You don't need to go Modal.

mkm wrote: ↑Mon May 14, 2018 6:00 amYou can't do this without possessing some meta-level notion on what these objects in logic "really" mean.

Which is why, in asserting more axioms, you're violating Occam's razor by claiming things about modal logic's relationship to reality when classical logic would suffice. It's not substantiated.

mkm wrote: ↑Mon May 14, 2018 6:00 amIf you don't see that your way of dealing with this is indistinguishable from "I model these things with modal logic", or you see it, but refuse to admit, there is nothing I can do.

It does the same job in some respects, but that doesn't make it philosophically identical. If you don't understand that, then there's nothing I can do to explain it to you.
It's what I see as your assertion of the supremacy of modal logic and the inferiority of classical logic that I take issue with.