Popperian epistemology still relies on deductive logic.
Uses, especially in science. Doesn’t rely on in any fundamental way for the main philosophical ideas.
Why is deductive logic trustworthy? (Serious question, I think it illuminates the nature of foundations)
It is not “trustworthy”. But I don’t have a criticism of it. I don’t reject ideas for no reason. Lacks of positive justification isn’t a reason (since nothing has justification, lack of it cannot differentiate between theories, so it isn’t a criticism to lack it).
What is “trustworthy” in an everyday sense, but not a strict philosophical sense, is knowledge. The higher quality an idea (i.e. the more it’s been improved up to now), the more trustworthy since the improvements consist of getting rid of mistakes, so there’s less mistakes to bite you. But how many mistakes are left, and how big are they? Unknown. So, it’s not trustworthy in any kind of definitive way.
You might argue that we conjecture that deductive logic, as we know it, is true/valid/correct and nothing that we’ve come up with seems to refute it—yet that doesn’t mean we’ve “proved” that deductive logic is correct.
Yes. We do conjecture it. And it’s not proved. So what?
A Bayesian might argue that the basic assumptions that go into Bayesian epistemology (The assumptions for Cox’s theorem + some assumptions that yield prior distributions) have the same status as the rules of logic.
A difference between Popperian views and justificationist ones is Popperian views don’t say anything should be justified and then fail to do it. But if you do say things should be justified, and then fail to do it, that is bad.
When Bayesians or inductivists set out to justify theories (and we mean that word broadly, e.g. “support” is a type of justification. So is “having high probability” when it is applied to ideas rather than to events.), they are proposing something rather different from logic. A difference is: justificationism has been criticized while logic hasn’t. The criticism is: if you say that theories should be justified, and you say that they gain their justification from other ideas which are themselves justified, then you get a regress. And if you don’t say that, you face the question: how are ideas to be justified? And you better have an answer. But no known answers work.
So justification has a different kind of status than logic. And also, if you accept justificationism then you face the problem of justifying logic. But if you don’t, then you don’t. So that’s why you have to, but we don’t.
So you might wonder what a non-justiificationist Bayesian epistemology would look like. If you’re interested, maybe you could tell me. I certainly do think that Bayes’ theorem itself is correct, but I’m not convinced it has any important applications to epistemology. I think that trying to have it play the role of justifying ideas is a mistake.
This is my understanding of Bayesian epistemology—something like (sophisticated) Popperian falsificationism / critical rationalism provides support for the assumptions of Bayesian epistemology. Then once you have the assumptions, well the rest falls out.
Popperians aren’t overly attached to any particular idea. Our favorites are things like fallibilism, not deduction. But we don’t have the structure of having some foundational ideas and then “the rest falls out”. We regard that kind of structure as fragile and bad. Popper said knowledge is like a “woven web”. There’s no up and down, no foundations and derivative parts, no preferred directions, and no simple structure like A → B → C. Everything is interconnected in messy fashion (much more so than real spider webs, which actually have relatively simple geometric patterns). And you are permitted to start in the middle, or anywhere, even in mid air. Whenever you want. It doesn’t matter. You can conjecture anything with no support, not just foundational ideas.
One of the problems with trying to use Popperian ideas for your foundations, then forgetting about them, is that they say you shouldn’t. If you let them in as your foundations, they will immediately tell you what to do next, and it isn’t Bayesian epistemology! They will tell you to be Popperians, and also to stop being foundationalists, they will not endorse your attempt to have “the rest fall out”. If Popper was right enough to serve as a foundation, why is he wrong about all the rest?
Another aspect of your approach is reductionism. You treat low level theories are more important. We consider that a mistake. There’s nothing wrong with emergent properties. There is nothing wrong with arguing from a higher level idea to a lower level one. Higher level ideas are just as valid as any others.
Why is deductive logic trustworthy? (Serious question, I think it illuminates the nature of foundations)
It is not “trustworthy”. But I don’t have a criticism of it.
I second here Khoth’s comment. How do you decide about validity of a criticism? There are certainly people who don’t understand logic, and since you have said
You can criticize any idea you want. There’s no rules again. If you don’t understand it, that’s a criticism—it should have been easier to understand.
doesn’t it mean that you actually have a criticism of logic? Or does only count that you personally don’t criticise it? If so, how this approach is different from accepting any idea at your wish? What’s the point of having an epistemology when it actually doesn’t constrain your beliefs in any way?
A technical question: how do I make nested quotes?
You conjecture standards of criticism, and use them. If you think they aren’t working well, you can criticize them within the system and change the, or you can conjecture new standards of criticism and use those. Note: this has already been done, and we already have standards of criticism which work pretty well and which allow themselves to be improved. (They are largely not uniquely Popperian, but well known.)
Different aspect: in general, all criticisms always have some valid point. If someone is making a criticism, and it’s wrong, then why wasn’t he helped enough not to do that? Theories should be clear and help people understand the world. If someone doesn’t get it then there is room for improvement.
doesn’t it mean that you actually have a criticism of logic?
I don’t regard logic as ‘rules’, in this context. But terminology is not important. The way logic figures into Popperian critical discussions is: if an idea violates logic you can criticize it for having done so. It would then in theory be possible to defend it by saying why this idea is out of the domain of logic or something (and of course you can point out if it doesn’t actually violate logic) -- there’s no rule against that. But no one has ever come up with a good argument of that type.
All criticisms have some kind of point, e.g. they might highlight a need for something to be explained better. This is compatible with saying no one ever came up with a good argument (good in the context of modern knowledge) for the Earth being flat, or something. If someone thinks the Earth is flat, then this is quite a good criticism of something—and I suspect that something is his own background knowledge. We could discus the matter. If he had some argument which addresses my round-earth views, i’d be interested. Or he might not know what they are. Shrug.
Another aspect of your approach is reductionism. You treat low level theories are more important. We consider that a mistake. There’s nothing wrong with emergent properties. There is nothing wrong with arguing from a higher level idea to a lower level one. Higher level ideas are just as valid as any others.
It is not “trustworthy”. But I don’t have a criticism of it. I don’t reject ideas for no reason.
Um, there’s a lot of criticism out there of deductive logic. For one thing, humans often make mistakes in deductive logic so one doesn’t know if something is correct. For another, some philosophers have rejected the law of the excluded middle. Yet others have proposed logical systems which try to localize contradictions and prevent explosions (under the sensible argument that when a person is presented with two contradictory logical arguments that look valid to them they don’t immediately decide that the moon is made of green cheese). There’s a lot to criticize about deductive logic.
Uses, especially in science. Doesn’t rely on in any fundamental way for the main philosophical ideas.
It is not “trustworthy”. But I don’t have a criticism of it. I don’t reject ideas for no reason. Lacks of positive justification isn’t a reason (since nothing has justification, lack of it cannot differentiate between theories, so it isn’t a criticism to lack it).
What is “trustworthy” in an everyday sense, but not a strict philosophical sense, is knowledge. The higher quality an idea (i.e. the more it’s been improved up to now), the more trustworthy since the improvements consist of getting rid of mistakes, so there’s less mistakes to bite you. But how many mistakes are left, and how big are they? Unknown. So, it’s not trustworthy in any kind of definitive way.
Yes. We do conjecture it. And it’s not proved. So what?
A difference between Popperian views and justificationist ones is Popperian views don’t say anything should be justified and then fail to do it. But if you do say things should be justified, and then fail to do it, that is bad.
When Bayesians or inductivists set out to justify theories (and we mean that word broadly, e.g. “support” is a type of justification. So is “having high probability” when it is applied to ideas rather than to events.), they are proposing something rather different from logic. A difference is: justificationism has been criticized while logic hasn’t. The criticism is: if you say that theories should be justified, and you say that they gain their justification from other ideas which are themselves justified, then you get a regress. And if you don’t say that, you face the question: how are ideas to be justified? And you better have an answer. But no known answers work.
So justification has a different kind of status than logic. And also, if you accept justificationism then you face the problem of justifying logic. But if you don’t, then you don’t. So that’s why you have to, but we don’t.
So you might wonder what a non-justiificationist Bayesian epistemology would look like. If you’re interested, maybe you could tell me. I certainly do think that Bayes’ theorem itself is correct, but I’m not convinced it has any important applications to epistemology. I think that trying to have it play the role of justifying ideas is a mistake.
Popperians aren’t overly attached to any particular idea. Our favorites are things like fallibilism, not deduction. But we don’t have the structure of having some foundational ideas and then “the rest falls out”. We regard that kind of structure as fragile and bad. Popper said knowledge is like a “woven web”. There’s no up and down, no foundations and derivative parts, no preferred directions, and no simple structure like A → B → C. Everything is interconnected in messy fashion (much more so than real spider webs, which actually have relatively simple geometric patterns). And you are permitted to start in the middle, or anywhere, even in mid air. Whenever you want. It doesn’t matter. You can conjecture anything with no support, not just foundational ideas.
One of the problems with trying to use Popperian ideas for your foundations, then forgetting about them, is that they say you shouldn’t. If you let them in as your foundations, they will immediately tell you what to do next, and it isn’t Bayesian epistemology! They will tell you to be Popperians, and also to stop being foundationalists, they will not endorse your attempt to have “the rest fall out”. If Popper was right enough to serve as a foundation, why is he wrong about all the rest?
Another aspect of your approach is reductionism. You treat low level theories are more important. We consider that a mistake. There’s nothing wrong with emergent properties. There is nothing wrong with arguing from a higher level idea to a lower level one. Higher level ideas are just as valid as any others.
I second here Khoth’s comment. How do you decide about validity of a criticism? There are certainly people who don’t understand logic, and since you have said
doesn’t it mean that you actually have a criticism of logic? Or does only count that you personally don’t criticise it? If so, how this approach is different from accepting any idea at your wish? What’s the point of having an epistemology when it actually doesn’t constrain your beliefs in any way?
A technical question: how do I make nested quotes?
You conjecture standards of criticism, and use them. If you think they aren’t working well, you can criticize them within the system and change the, or you can conjecture new standards of criticism and use those. Note: this has already been done, and we already have standards of criticism which work pretty well and which allow themselves to be improved. (They are largely not uniquely Popperian, but well known.)
Different aspect: in general, all criticisms always have some valid point. If someone is making a criticism, and it’s wrong, then why wasn’t he helped enough not to do that? Theories should be clear and help people understand the world. If someone doesn’t get it then there is room for improvement.
I don’t regard logic as ‘rules’, in this context. But terminology is not important. The way logic figures into Popperian critical discussions is: if an idea violates logic you can criticize it for having done so. It would then in theory be possible to defend it by saying why this idea is out of the domain of logic or something (and of course you can point out if it doesn’t actually violate logic) -- there’s no rule against that. But no one has ever come up with a good argument of that type.
Isn’t this
contradicting this
?
I mean, if you can judge arguments and say whether they are good, doesn’t it mean that there are bad arguments which don’t have a valid point?
All criticisms have some kind of point, e.g. they might highlight a need for something to be explained better. This is compatible with saying no one ever came up with a good argument (good in the context of modern knowledge) for the Earth being flat, or something. If someone thinks the Earth is flat, then this is quite a good criticism of something—and I suspect that something is his own background knowledge. We could discus the matter. If he had some argument which addresses my round-earth views, i’d be interested. Or he might not know what they are. Shrug.
This works for me. However, I want to quote something inside a quote and then continue on the first level, such as
The text in italic should be one quoting level deeper.
Yields
Thanks!
No, that’s incorrect. That may be how other philosophers use the term, but that’s not what it means here.
Edit: To clarify, I mean that LessWrong doesn’t define reductionism the same way you just did, so your argument doesn’t apply.
Um, there’s a lot of criticism out there of deductive logic. For one thing, humans often make mistakes in deductive logic so one doesn’t know if something is correct. For another, some philosophers have rejected the law of the excluded middle. Yet others have proposed logical systems which try to localize contradictions and prevent explosions (under the sensible argument that when a person is presented with two contradictory logical arguments that look valid to them they don’t immediately decide that the moon is made of green cheese). There’s a lot to criticize about deductive logic.