I don’t know the etiquette or format of this website well or how it works. When I have comments on the book, would it make sense to start a new thread or post somewhere/somehow?
Can you be a Popperian and conjecture Bayesianism?
You can conjecture Bayes’ theorem. You can also conjecture all the rest, however some things (such as induction, justificationism, foundationalism) contradict Popper’s epistemology. So at least one of them has a mistake to fix. Fixing that may or may not lead to drastic changes, abandonment of the main ideas, etc
The point that I do disagree with is the proposed asymmetry between confirmation and falsification.
That is a purely logical point Popper used to criticize some mistaken ideas. Are you disputing the logic? If you’re merely disputing the premises, it doesn’t really matter because its purpose is to criticize people who use those premises on their own terms.
In my view neither the black swan or the white swan proves anything with certainty,
Agreed.
but both do provide some evidence. It happens in this case that one piece of evidence is very strong while the other is very weak, in fact they are pretty much at opposite extremes of the full spectrum of evidence encountered in the real world. This does not mean there is a difference of type.
I think you are claiming that seeing a white swan is positive support for the assertion that all swans are white. (If not, please clarify). If so, this gets into important issues. Popper disputed the idea of positive support. The criticism of the concept begins by considering: what is support? And in particular, what is the difference between “X supports Y” and “X is consistent with Y”?
I also doubt that any philosophy could manage without either circularity or assumptions, explicit or otherwise. As I see it when you start thinking you need something to begin your inference, logic derives truths form other truths, it cannot manufacture them out of a vacuum.
Questioning this was one of Popper’s insights. The reason most people doubt it is possible is because, since Aristotle, pretty much all epistemology has taken this for granted. These ideas seeped into our culture and became common sense.
What’s weird about the situation is that most people are so attached to them that they are willing to accept circular arguments, arbitrary foundations, or other things like that. Those are OK! But that Popper might have a point is hard to swallow. I find circular arguments rather more doubtful than doing without what Popperians refer to broadly as “justification”. I think it’s amazing that people run into circularity or other similar problems and still don’t want to rethink all their premises. (No offense intended. Everyone has biases, and if we try to overcome them we can become less wrong about some matters, and stating guesses at what might be biases can help with that.)
All the circularity and foundations stem from seeking to justify ideas. To show they are correct. Popper’s epistemology is different: ideas never have any positive support, confirmation, verification, justification, high probability, etc… So how do we act? How do we decide which idea is better than the others? We can differentiate ideas by criticism. When we see a mistake in an idea, we criticize it (criticism = explaining a mistake/flaw). That refutes the idea. We should act on or use non-refuted ideas in preference over refuted ideas.
That’s the very short outline, but does that make any sense?
You can conjecture Bayes’ theorem. You can also conjecture all the rest, however some things (such as induction, justificationism, foundationalism) contradict Popper’s epistemology. So at least one of them has a mistake to fix. Fixing that may or may not lead to drastic changes, abandonment of the main ideas, etc
Fully agreed. In principle, if Popper’s epistemology is of the second, self-modifying type, there would be nothing wrong with drastic changes. One could argue that something like that is exactly how I arrived at my current beliefs, I wasn’t born a Bayesian.
I can also see some ways to make induction and foundationalism easer to swallow.
I don’t know the etiquette or format of this website well or how it works. When I have comments on the book, would it make sense to start a new thread or post somewhere/somehow?
A discussion post sounds about right for this, if enough people like it you might consider moving it to the main site.
I think you are claiming that seeing a white swan is positive support for the assertion that all swans are white. (If not, please clarify).
This is precisely what I am saying.
If so, this gets into important issues. Popper disputed the idea of positive support. The criticism of the concept begins by considering: what is support? And in particular, what is the difference between “X supports Y” and “X is consistent with Y”?
The beauty of Bayes is how it answers these questions. To distinguish between the two statements we express them each in terms of probabilities.
“X is consistent with Y” is not really a Bayesian way of putting things, I can see two ways of interpreting it. One is as P(X&Y) > 0, meaning it is at least theoretically possible that both X and Y are true. The other is that P(X|Y) is reasonably large, i.e. that X is plausible if we assume Y.
“X supports Y” means P(Y|X) > P(Y), X supports Y if and only if Y becomes more plausible when we learn of X. Bayes tells us that this is equivalent to P(X|Y) > P(X), i.e. if Y would suggest that X is more likely that we might think otherwise then X is support of Y.
Suppose we make X the statement “the first swan I see today is white” and Y the statement “all swans are white”. P(X|Y) is very close to 1, P(X|~Y) is less than 1 so P(X|Y) > P(X), so seeing a white swan offers support for the view that all swans are white. Very, very weak support, but support nonetheless.
(The above is not meant to be condescending, I apologise if you know all of it already).
To show they are correct. Popper’s epistemology is different: ideas never have any positive support, confirmation, verification, justification, high probability, etc...
This is a very tough bullet to bite.
How do we decide which idea is better than the others? We can differentiate ideas by criticism. When we see a mistake in an idea, we criticize it (criticism = explaining a mistake/flaw). That refutes the idea. We should act on or use non-refuted ideas in preference over refuted ideas.
One thing I don’t like about this is the whole ‘one strike and you’re out’ feel of it. It’s very boolean, the real world isn’t usually so crisp. Even a correct theory will sometimes have some evidence pointing against it, and in policy debates almost every suggestion will have some kind of downside.
There is also the worry that there could be more than one non-refuted idea, which makes it a bit difficult to make decisions. Bayesianism, on the other hand, when combined with expected utility theory, is perfect for making decisions.
I haven’t got any faith in human intuition. That’s not what I said.
OK fair enough.
Oh the book is here: http://bayes.wustl.edu/etj/prob/book.pdf
That was easy.
I don’t know the etiquette or format of this website well or how it works. When I have comments on the book, would it make sense to start a new thread or post somewhere/somehow?
You can conjecture Bayes’ theorem. You can also conjecture all the rest, however some things (such as induction, justificationism, foundationalism) contradict Popper’s epistemology. So at least one of them has a mistake to fix. Fixing that may or may not lead to drastic changes, abandonment of the main ideas, etc
That is a purely logical point Popper used to criticize some mistaken ideas. Are you disputing the logic? If you’re merely disputing the premises, it doesn’t really matter because its purpose is to criticize people who use those premises on their own terms.
Agreed.
I think you are claiming that seeing a white swan is positive support for the assertion that all swans are white. (If not, please clarify). If so, this gets into important issues. Popper disputed the idea of positive support. The criticism of the concept begins by considering: what is support? And in particular, what is the difference between “X supports Y” and “X is consistent with Y”?
Questioning this was one of Popper’s insights. The reason most people doubt it is possible is because, since Aristotle, pretty much all epistemology has taken this for granted. These ideas seeped into our culture and became common sense.
What’s weird about the situation is that most people are so attached to them that they are willing to accept circular arguments, arbitrary foundations, or other things like that. Those are OK! But that Popper might have a point is hard to swallow. I find circular arguments rather more doubtful than doing without what Popperians refer to broadly as “justification”. I think it’s amazing that people run into circularity or other similar problems and still don’t want to rethink all their premises. (No offense intended. Everyone has biases, and if we try to overcome them we can become less wrong about some matters, and stating guesses at what might be biases can help with that.)
All the circularity and foundations stem from seeking to justify ideas. To show they are correct. Popper’s epistemology is different: ideas never have any positive support, confirmation, verification, justification, high probability, etc… So how do we act? How do we decide which idea is better than the others? We can differentiate ideas by criticism. When we see a mistake in an idea, we criticize it (criticism = explaining a mistake/flaw). That refutes the idea. We should act on or use non-refuted ideas in preference over refuted ideas.
That’s the very short outline, but does that make any sense?
Fully agreed. In principle, if Popper’s epistemology is of the second, self-modifying type, there would be nothing wrong with drastic changes. One could argue that something like that is exactly how I arrived at my current beliefs, I wasn’t born a Bayesian.
I can also see some ways to make induction and foundationalism easer to swallow.
A discussion post sounds about right for this, if enough people like it you might consider moving it to the main site.
This is precisely what I am saying.
The beauty of Bayes is how it answers these questions. To distinguish between the two statements we express them each in terms of probabilities.
“X is consistent with Y” is not really a Bayesian way of putting things, I can see two ways of interpreting it. One is as P(X&Y) > 0, meaning it is at least theoretically possible that both X and Y are true. The other is that P(X|Y) is reasonably large, i.e. that X is plausible if we assume Y.
“X supports Y” means P(Y|X) > P(Y), X supports Y if and only if Y becomes more plausible when we learn of X. Bayes tells us that this is equivalent to P(X|Y) > P(X), i.e. if Y would suggest that X is more likely that we might think otherwise then X is support of Y.
Suppose we make X the statement “the first swan I see today is white” and Y the statement “all swans are white”. P(X|Y) is very close to 1, P(X|~Y) is less than 1 so P(X|Y) > P(X), so seeing a white swan offers support for the view that all swans are white. Very, very weak support, but support nonetheless.
(The above is not meant to be condescending, I apologise if you know all of it already).
This is a very tough bullet to bite.
One thing I don’t like about this is the whole ‘one strike and you’re out’ feel of it. It’s very boolean, the real world isn’t usually so crisp. Even a correct theory will sometimes have some evidence pointing against it, and in policy debates almost every suggestion will have some kind of downside.
There is also the worry that there could be more than one non-refuted idea, which makes it a bit difficult to make decisions. Bayesianism, on the other hand, when combined with expected utility theory, is perfect for making decisions.
When replying it said “comment too long” so I posted my reply here:
http://lesswrong.com/r/discussion/lw/552/reply_to_benelliott_about_popper_issues/