That the empirical world exists is a supposition you were born into. The argument is over whether that’s satisfying enough to be called an explanation.
My previous reply wasn’t very helpful, sorry. Let me reiterate what I said above: making assumptions isn’t so much rational as unavoidable. And so you ask “then, should we believe in the external world?”
Well, this question has two answers. The first is that there is no argument that will convince an agent who didn’t make any assumptions that they should believe in an external world. In fact, there is no truth so self-evident it can convince any reasoner. For an illustration of this, see What the Tortoise Said to Achilles. Thus, from a perspective that makes no assumptions, no assumption is particularly better than another.
There is a problem with the first answer, though. This is that “the perspective that makes no assumptions” is the epistemological equivalent of someone with a rock in their head. It’s even worse than the tortoise—it can’t talk, it can’t reason, because it doesn’t assume even provisionally that the external world exists or that (A and A->B) → B. You can’t convince it of anything not because all positions are unworthy, but because there’s no point trying to convince a rock.
The second answer is that of course you should believe in the external world, and common sense, and all that good stuff. Now, you may say “but you’re using your admittedly biased brain to say that, so it’s no good,” but, I ask you, what else should I use? My kidneys?
If you prefer a slightly more sophisticated treatment, consider different agents interpreting “should we believe in the external world” with different meanings of the word “should”. We can call ours human_should, and yes, you human_should believe in the external world. But the word no_assumptions_should does not, in fact, have a definition, because the agent with no assumptions, the guy with a rock in his head, does not assume up any standards to judge actions with. Lacking this alternative, the human_reasonable course of action is to interpret your question as “”human_should we believe in the external world,” to which the answer is yes.
The second answer is that of course you should believe in the external world, and common sense, and all that good stuff. Now, you may say “but you’re using your admittedly biased brain to say that, so it’s no good,” but, I ask you, what else should I use? My kidneys?
This is the place to whip out the farmer/directions joke. The one that ends, “you just can’t get there from here.”
I’d already considered the “What the Tortoise said to Achilles” argument in a different form. I’d gotten around it (I was arguing Foundationalism until now, remember) by redefining self-evident as:
What must be true in any possible universe.
If a truth is self-evident, then a universe where it was false simply COULD NOT EXIST for one reason or another. Elizier has described a non-Reductionist universe the way I believe a legitimate self-evident truth (by this definition) should be described. To those who object, I call it self-evident’ (self evident dash, as I say it in normal conversation) and use it instead of self-evident as a basis for justification.
The Foundationalist skeptics in the debate would laugh at your argument, point out you can’t even assume the existence of a brain with justification, nor the existence of “should” either in the human sense or any other. Thus your argument falls apart.
I agree with the foundationalist skeptics, except for that anything “falls apart” is, of course, something that they just assume without justification, and should be discarded :)
Self-evident from the definition of rational: It is irrational to believe a proposistion if you have no evidence for or against it.
Empirical evidence is not evidence if you have no reason to trust it. Therefore, the fact that your argument falls apart is self-evident given the premises and conclusions therein.
The “definition of rational” is already without foundation—see again What the Tortoise Said to Achilles, and No Universally Convincing Arguments.
Or perhaps I’m overestimating how skeptical normal skepticism is? Is it normal for foundationalist skeptics to say that there’s no reason to believe the external world, but that we have to follow certain laws of thought “by definition,” and thus be unable to believe the Tortoise could exist? That’s not a rhetorical question, I’m pretty ignorant about this stuff.
I’ve already gotten past the arguments in those two cases by redefining self-evident by reference to what must be true in any possible universe. Elizier himself describes reductionism in a way which fits my new idea of self-evident. The Foundationalist skeptics agree with me. As for the definition of rational, if you understand nominalism you will see why the definition is beyond dispute.
The Foundationalist Skeptic supports starting from no assumptions except those that can be demonstrated to be self-evident.
The Foundationalist Skeptic supports starting from no assumptions except those that can be demonstrated to be self-evident.
So, you agree that the Foundationalist Skeptic rejects the use of modus ponens, since Achilles cannot possibly convince the Tortoise to use it?
Also, I recommend this post. You seem to be roving into that territory. And calling anything, even modus ponens, “beyond dispute” only works within a certain framework of what is disputable—someone with a different framework (the tortoise) may think their framework is beyond dispute. In short, the reflective equilibrium of minds does not have just one stable point.
Just to remind you, I am not TECHNICALLY arguing for Foundationalist skepticism here. My argument is that it doesn’t have any major weaknesses OTHER THAN the ones I’ve already mentioned.
Regarding the use of modus ponens, that WAS a problem until I redefined self-evident to refer to what must be true in any possible universe. This is a mind-independent definition of self-evident.
I suspect a Foundationalist skeptic shouldn’t engage with Elizier’s arguments in this case as it appeals to empirical evidence, but leaving that aside the ordinary definition of ‘rational’ contains a contradiction. In ordinary cases of “rationality”, if somebody claims A because of X and are asked “Why should I trust X?”, the claimer is expected to have an answer for why X is trustworthy.
The four possible solutions to this are Weak Foundationalism (end up in first causes they can’t justify), Infinitism(infinite regress), Coherentism(believe because knowledge coheres), and Strong Foundationalism. This excludes appealing to Common Sense, as Common Sense is both incoherent and commonly considered incompatible with Rationality.
A Weak Foundationalist is challengable on privledging their starting points, plus the fact that any reason they give for privledging said starting points is itself a reason for their starting point and hence another stage back. Infinitism and Coherentism have the problem that without a first cause we have no reason to believe they cohere with reality. This leaves Strong Foundationalism by default.
self-evident to refer to what must be true in any possible universe. This is a mind-independent definition of self-evident.
So why doesn’t the Tortoise agree that modus ponens is true in any possible universe? Do you have some special access to truth that the Tortoise doesn’t? If you don’t, isn’t this just an unusual Neurathian vessel of the nautical kind?
What the Tortoise believes is irrelevant. In any universe whatsoever, proper modus ponens will work. Another way of showing is that a universe where it doesn’t work would be internally incoherent. Arguments are mind-independent- whether my mind has a special acess to truth or not (theoretically, I may simply have gotten it right this time and this time only), my arguments are just as valid.
Elizier is right to say that you can’t argue with a rock. However, insane individuals who disagree in the Tortoise case are irrelevant because the reasoning is not based on universial agreement of first premises but the fact that in any possible universe the premises must be true.
I agree—modus ponens works, even though there are some minds who will reject it with internally coherent criteria. Even criteria as simple as “modus ponens works, except when it will lead to belief in the primness of 7 being added to your belief pool”—this definition defends itself because if it was wrong, you could prove 7 was prime, therefore it’s not wrong.
You could be put in a room with one off these 7-denialists, and no argument you made could convince them that they had the wrong form of modus ponens, and you had the right one.
But try seeing it from their perspective. To them, 7 not being prime is just how it is. To them, you’re the 7-denialist, and they’ve been put in a room with you, yet are unable to convince you that you have the wrong form of modus ponens, and they have the right one.
Suppose you try to show that a universe where 7 isn’t prime is internally inconsistent. What would the proof look like? Well, it would look like some axioms of arithmetic, which you and the 7-denialists share. Then you’d apply modus ponens to these axioms, until you reached the conclusion that 7 is prime, and thus any system with “7 is not prime” added to the basic axioms would be inconsistent.
What would the 7-denialist you’re in a room with say to that? I think it’s pretty clear—they’d say that you’re making a very elementary mistake, you’re just applying modus ponens wrong. In the step where you go from 7 not being factorable into 2, 3, 4, 5 or 6, to 7 being prime, you’ve committed a logical fallacy, and have not shown that 7 is prime from the basic axioms. Therefore you cannot rule out that 7 is not prime, and your version of modus ponens is therefore not true in every possible universe.
Just because you can use something to prove itself, they say, doesn’t mean it’s right in every possible universe. You should try to be a little more cosmopolitan and seriously consider that 7 isn’t prime.
I’m guessing you disagree with Elizier’s thoughts on Reductionism, then?
The 7-denialists are making a circular argument with your first defence of their posistion. Circular arguments aren’t self-evidently wrong, but they are self-evidently not evidence as there isn’t justification for believing any of them. The argument for conventional modus ponens is not a circular argument.
The second argument would be that the 7-denialists are making an additional assumption they haven’t proven, whilst the Foundationalist Skeptic starts with no assumptions. That there is an inconsistency in 7 being prime needs demonstrating, after all. If you redefine Prime to exclude 7 then it is strictly correct and we don’t have a disagreement, but we don’t need a different logic for that. (And the standard defintition of Prime is more mathematically useful)
Finally, the Foundationalist Skeptic would argue that they aren’t using something to prove itself- they are starting from no starting assumptions whatsoever. I have concluded, as I mentioned, that there is a problem with their posistion, but not the one you claim.
That the empirical world exists is a supposition you were born into. The argument is over whether that’s satisfying enough to be called an explanation.
The argument is about whether the belief is rational or irrational. Discussing it in the manner you describe is off the point,
My previous reply wasn’t very helpful, sorry. Let me reiterate what I said above: making assumptions isn’t so much rational as unavoidable. And so you ask “then, should we believe in the external world?”
Well, this question has two answers. The first is that there is no argument that will convince an agent who didn’t make any assumptions that they should believe in an external world. In fact, there is no truth so self-evident it can convince any reasoner. For an illustration of this, see What the Tortoise Said to Achilles. Thus, from a perspective that makes no assumptions, no assumption is particularly better than another.
There is a problem with the first answer, though. This is that “the perspective that makes no assumptions” is the epistemological equivalent of someone with a rock in their head. It’s even worse than the tortoise—it can’t talk, it can’t reason, because it doesn’t assume even provisionally that the external world exists or that (A and A->B) → B. You can’t convince it of anything not because all positions are unworthy, but because there’s no point trying to convince a rock.
The second answer is that of course you should believe in the external world, and common sense, and all that good stuff. Now, you may say “but you’re using your admittedly biased brain to say that, so it’s no good,” but, I ask you, what else should I use? My kidneys?
If you prefer a slightly more sophisticated treatment, consider different agents interpreting “should we believe in the external world” with different meanings of the word “should”. We can call ours human_should, and yes, you human_should believe in the external world. But the word no_assumptions_should does not, in fact, have a definition, because the agent with no assumptions, the guy with a rock in his head, does not assume up any standards to judge actions with. Lacking this alternative, the human_reasonable course of action is to interpret your question as “”human_should we believe in the external world,” to which the answer is yes.
This is the place to whip out the farmer/directions joke. The one that ends, “you just can’t get there from here.”
“I say, farmer, you’re pretty close to a fool, ain’t’cha?”
“Yup, only this here fence between us.”
I’d already considered the “What the Tortoise said to Achilles” argument in a different form. I’d gotten around it (I was arguing Foundationalism until now, remember) by redefining self-evident as:
What must be true in any possible universe.
If a truth is self-evident, then a universe where it was false simply COULD NOT EXIST for one reason or another. Elizier has described a non-Reductionist universe the way I believe a legitimate self-evident truth (by this definition) should be described. To those who object, I call it self-evident’ (self evident dash, as I say it in normal conversation) and use it instead of self-evident as a basis for justification.
The Foundationalist skeptics in the debate would laugh at your argument, point out you can’t even assume the existence of a brain with justification, nor the existence of “should” either in the human sense or any other. Thus your argument falls apart.
I agree with the foundationalist skeptics, except for that anything “falls apart” is, of course, something that they just assume without justification, and should be discarded :)
Self-evident from the definition of rational: It is irrational to believe a proposistion if you have no evidence for or against it.
Empirical evidence is not evidence if you have no reason to trust it. Therefore, the fact that your argument falls apart is self-evident given the premises and conclusions therein.
The “definition of rational” is already without foundation—see again What the Tortoise Said to Achilles, and No Universally Convincing Arguments.
Or perhaps I’m overestimating how skeptical normal skepticism is? Is it normal for foundationalist skeptics to say that there’s no reason to believe the external world, but that we have to follow certain laws of thought “by definition,” and thus be unable to believe the Tortoise could exist? That’s not a rhetorical question, I’m pretty ignorant about this stuff.
I’ve already gotten past the arguments in those two cases by redefining self-evident by reference to what must be true in any possible universe. Elizier himself describes reductionism in a way which fits my new idea of self-evident. The Foundationalist skeptics agree with me. As for the definition of rational, if you understand nominalism you will see why the definition is beyond dispute.
The Foundationalist Skeptic supports starting from no assumptions except those that can be demonstrated to be self-evident.
So, you agree that the Foundationalist Skeptic rejects the use of modus ponens, since Achilles cannot possibly convince the Tortoise to use it?
Also, I recommend this post. You seem to be roving into that territory. And calling anything, even modus ponens, “beyond dispute” only works within a certain framework of what is disputable—someone with a different framework (the tortoise) may think their framework is beyond dispute. In short, the reflective equilibrium of minds does not have just one stable point.
Just to remind you, I am not TECHNICALLY arguing for Foundationalist skepticism here. My argument is that it doesn’t have any major weaknesses OTHER THAN the ones I’ve already mentioned.
Regarding the use of modus ponens, that WAS a problem until I redefined self-evident to refer to what must be true in any possible universe. This is a mind-independent definition of self-evident.
I suspect a Foundationalist skeptic shouldn’t engage with Elizier’s arguments in this case as it appeals to empirical evidence, but leaving that aside the ordinary definition of ‘rational’ contains a contradiction. In ordinary cases of “rationality”, if somebody claims A because of X and are asked “Why should I trust X?”, the claimer is expected to have an answer for why X is trustworthy.
The four possible solutions to this are Weak Foundationalism (end up in first causes they can’t justify), Infinitism(infinite regress), Coherentism(believe because knowledge coheres), and Strong Foundationalism. This excludes appealing to Common Sense, as Common Sense is both incoherent and commonly considered incompatible with Rationality.
A Weak Foundationalist is challengable on privledging their starting points, plus the fact that any reason they give for privledging said starting points is itself a reason for their starting point and hence another stage back. Infinitism and Coherentism have the problem that without a first cause we have no reason to believe they cohere with reality. This leaves Strong Foundationalism by default.
So why doesn’t the Tortoise agree that modus ponens is true in any possible universe? Do you have some special access to truth that the Tortoise doesn’t? If you don’t, isn’t this just an unusual Neurathian vessel of the nautical kind?
What the Tortoise believes is irrelevant. In any universe whatsoever, proper modus ponens will work. Another way of showing is that a universe where it doesn’t work would be internally incoherent. Arguments are mind-independent- whether my mind has a special acess to truth or not (theoretically, I may simply have gotten it right this time and this time only), my arguments are just as valid.
Elizier is right to say that you can’t argue with a rock. However, insane individuals who disagree in the Tortoise case are irrelevant because the reasoning is not based on universial agreement of first premises but the fact that in any possible universe the premises must be true.
I agree—modus ponens works, even though there are some minds who will reject it with internally coherent criteria. Even criteria as simple as “modus ponens works, except when it will lead to belief in the primness of 7 being added to your belief pool”—this definition defends itself because if it was wrong, you could prove 7 was prime, therefore it’s not wrong.
You could be put in a room with one off these 7-denialists, and no argument you made could convince them that they had the wrong form of modus ponens, and you had the right one.
But try seeing it from their perspective. To them, 7 not being prime is just how it is. To them, you’re the 7-denialist, and they’ve been put in a room with you, yet are unable to convince you that you have the wrong form of modus ponens, and they have the right one.
Suppose you try to show that a universe where 7 isn’t prime is internally inconsistent. What would the proof look like? Well, it would look like some axioms of arithmetic, which you and the 7-denialists share. Then you’d apply modus ponens to these axioms, until you reached the conclusion that 7 is prime, and thus any system with “7 is not prime” added to the basic axioms would be inconsistent.
What would the 7-denialist you’re in a room with say to that? I think it’s pretty clear—they’d say that you’re making a very elementary mistake, you’re just applying modus ponens wrong. In the step where you go from 7 not being factorable into 2, 3, 4, 5 or 6, to 7 being prime, you’ve committed a logical fallacy, and have not shown that 7 is prime from the basic axioms. Therefore you cannot rule out that 7 is not prime, and your version of modus ponens is therefore not true in every possible universe.
Just because you can use something to prove itself, they say, doesn’t mean it’s right in every possible universe. You should try to be a little more cosmopolitan and seriously consider that 7 isn’t prime.
I’m guessing you disagree with Elizier’s thoughts on Reductionism, then?
The 7-denialists are making a circular argument with your first defence of their posistion. Circular arguments aren’t self-evidently wrong, but they are self-evidently not evidence as there isn’t justification for believing any of them. The argument for conventional modus ponens is not a circular argument.
The second argument would be that the 7-denialists are making an additional assumption they haven’t proven, whilst the Foundationalist Skeptic starts with no assumptions. That there is an inconsistency in 7 being prime needs demonstrating, after all. If you redefine Prime to exclude 7 then it is strictly correct and we don’t have a disagreement, but we don’t need a different logic for that. (And the standard defintition of Prime is more mathematically useful)
Finally, the Foundationalist Skeptic would argue that they aren’t using something to prove itself- they are starting from no starting assumptions whatsoever. I have concluded, as I mentioned, that there is a problem with their posistion, but not the one you claim.
Well if you say so. Best of luck then.