## Using False Theories

C&R by Popper p 306
we are, in many cases, quite well served by theories which are known to be false.
This is a mistake! Consider a theory of motion, say, which we'll call T. We know T is false, but it's also a good approximation to the truth in common and well defined circumstances.

We do not use theory T. We use theory U which consists of what I said in the first paragraph: that theory T is an approximation, and useful in certain circumstances. Theory U contains in it theory T, but also some other ideas including the refutation of T. Theory U is a way of approximating motion in certain circumstances, it's useful, and it's not known to be false. Theory U is just plain better.

If we can't create a true variant of T or any other false theory, like we did with U, then T is not actually useful at all. Refuted theories can only be useful via non-refuted theories that make reference to them, not on their own.

Elliot Temple on March 8, 2010

I wonder if its not just that we are using an approximation, but that in limited circumstances, a *false* theory might have more truth than the theory we haven't determined yet to be false.

The world is round is true. The world is flat is false. But in our ordinary experience, perhaps more truth can be derived from the false theory than the true one, so in those circumstance we prefer it.

Is that possible?

Matt D. at 6:06 PM on March 8, 2010 | #1976 | reply | quote

"The world is round, and in various circumstances this can be misleading and pretending the world is flat can work pretty well" trumps them both. It's the true theory + addenda about possible errors and their solution. (Note: in real life to do anything useful we'd want a more detailed theory than what I typed in here. It'd say when the true theory is misleading, why, and more specifically what to do about it.)

Any refuted theory T is strictly inferior to a non-refuted theory which has 3 parts:

1) says T is refuted due to argument X

2) contains T

3) explains the circumstances in which T has some uses.

Elliot at 6:18 PM on March 8, 2010 | #1977 | reply | quote

A theory cannot contain a theory and it's refutation. It would be a contradiction.

And we are quite well served by false theories. Newton's theiory was used for ages without being know to be false, but it was still false. We did not use the theory that it was approximately true. A refutation of a theory does not render it unusable. We can still use it exactly the same way.

I think also yiur claim should be tested against the failure of Verisimilitide, it seems to take for granted that this problem has been solved. It is hard to know where something approximates the truth, simply because there is no measure of it. The theory U would have to contain that.

Anonymous at 5:00 PM on December 21, 2016 | #7994 | reply | quote

> A theory cannot contain a theory and it's refutation. It would be a contradiction.

nonsense. e.g. a theory can look like this: I think A, B, C, D, E, F, G are theories.

And B could refute A.

plus contradiction doesn't prevent something from being a theory. lots of theories are wrong. you even immediately state that not only are there false theories by they may be valuable: "And we are quite well served by false theories."

> A refutation of a theory does not render it unusable. We can still use it exactly the same way.

not exactly the same way. you need a theory of how to use it which isn't refuted. you can't use the original. you need a theory like "Newton's laws are refuted in general, but still work to solve the following problems... because..."

curi at 5:15 PM on December 21, 2016 | #7995 | reply | quote

also #7994 you don't quote anything which leaves it really unclear what you're replying to or what your point is supposed to be. e.g. did you think a particular idea written somewhere above was wrong? which idea and why is it wrong?

curi at 5:17 PM on December 21, 2016 | #7996 | reply | quote

It do want to add something that might be useful, though this pronlem has not been solved yet, if a theory has a true and false content (ie it is false) we can sequester the true statements and the true statements together would constitute another true theory.

What this implies I think is that new theory , the one you call U, would not contains the statement "theory T is criticised by X) instead this would be outside the empirical theories, T and U., though, X, itself might be a part of theory U. Since X is a test report, that must be explained by any new theory, that wishes to overcome the mistakes of previous s theories. This would mean that U would have to keep changing every time we find a new false consequence of T. That means that U itself would have another theory, theory V, say, which shows that U is also approximate.

Anonymous at 5:17 PM on December 21, 2016 | #7997 | reply | quote

>nonsense. e.g. a theory can look like this: I think A, B, C, D, E, F, G are theories.

And B could refute A.

plus contradiction doesn't prevent something from being a theory. lots of theories are wrong. you even immediately state that not only are there false theories by they may be valuable: "And we are quite well served by false theories."

Obviously,Mehta you are saying is true. All I mean to say is that U is not true, if it contains a theory and it's refutation. Since it would be contradictory and is therefore no better than T, since it was the falsity you were trying to overcome.

Anonymous at 5:23 PM on December 21, 2016 | #7998 | reply | quote

not exactly the same way. you need a theory of how to use it which isn't refuted. you can't use the original. you need a theory like "Newton's laws are refuted in general, but still work to solve the following problems... because..."

but we are still using the axioms of Newton's theory withing the domain limit, we are not using another theory. Since the madder extra only says you should not use it ousted this particular boundary. That only sets limits it does not change the calculation, or the laws we have tpused to make the calculation. So we are still using the original false theory.

Anonymous at 5:35 PM on December 21, 2016 | #7999 | reply | quote

My contention here, is that the explanation of the boundary is outside the theory.

Anonymous at 5:38 PM on December 21, 2016 | #8000 | reply | quote

> All I mean to say is that U is not true, if it contains a theory and it's refutation.

what is your point? and you're still reusing the word "contains" wrong, when you mean *asserts*.

you seem to be replying to some non-quoted previous material. your comments aren't self-contained and don't have references to the relevant other stuff. this makes them very hard to follow. especially when dealing with old stuff that isn't fresh in people's minds.

> Obviously

the truth isn't obvious.

> It do want to add something that might be useful, though this pronlem has not been solved yet

the problem of re-using ideas from refuted theories is solved. you make a new theory which isn't refuted and use that. sequestering is one approach to designing the new theory.

---

PS you need to quote every paragraph when quoting multiple paragraphs. you pasted some quotes as plain text that looks like your own new reply text.

Anonymous at 5:39 PM on December 21, 2016 | #8001 | reply | quote

> My contention here, is that the explanation of the boundary is outside the theory.

what problem are you trying to solve by this separation?

generally you can divide up ideas in lots of different ways, some are useful, and some aren't. you seem to think there's only one way that idea divisions simply are (in the world of forms? in the brains of everyone who has the idea, and no one thinks about it multiple ways?) and it's worth arguing over for some unstated reason.

> but we are still using the axioms of Newton's theory withing the domain limit, we are not using another theory. Since the madder extra only says you should not use it ousted this particular boundary. That only sets limits it does not change the calculation, or the laws we have tpused to make the calculation. So we are still using the original false theory.

withing? madder? tpused? and other errors. and you use jargon like "the domain limit" without explanation. you're being too careless. i don't think it's worth continuing for me if you don't make a major effort. all i see is a confused person being careless about an issue i understand and he doesn't, trying to say something which i understand and which is wrong and boring. so i don't see that i'll learn from them or that they'll learn much either (due to the carelessness -- learning much takes an effort). so where's the value for me or for anyone?

curi at 5:44 PM on December 21, 2016 | #8002 | reply | quote

my point came right after the sentence you quoted,.

>"and you're still reusing the word "contains" wrong, when you mean *asserts*."

You are the one that said contains.

> Theory U contains in it theory T, but also some other ideas including the refutation of T

You cannot have both T and the refutation of T inside a theory, and it still be a true theory. Which is exactly what you said U was.

You could just say that theory U contains a subset of T, it's truth content.p and the true test report.

I am just trying to point out to you that retransmission of falsity does not give you a clue about what other predictions from the theory might be false. So just adding that X is approximate foes not help, because it's approximation needs a new theory, but even then we cannot do this, because a measure of approximates to truth has not been created, so we are using false theories without this. and for ithe idea that we can supplement the thoeory with it works in X domain does not make a new emprical theory. It is an instruction on how to use the false theory and its limits.

Anonymous at 6:04 PM on December 21, 2016 | #8003 | reply | quote

anon wrote:

> > A theory cannot contain a theory and it's refutation. It would be a contradiction.

anon wrote:

> You are the one that said contains.

you are not paying attention. this seems like a waste of time

> I am just trying to point out to you that retransmission of falsity does not give you a clue about what other predictions from the theory might be false.

you haven't said why you're trying to point that out, and you didn't mention it until now. i think you're really bad at communication. do you want to learn to think and communicate? you could begin studying now and solve lots of problems.

Anonymous at 6:09 PM on December 21, 2016 | #8004 | reply | quote

>what problem are you trying to solve by this separation?

If U asserts that the theory T is false, which is just equivalent to ~T, then it contains ~T. But U also contains (or asserts) T. So U cannot also assert T and ~T and be useful or true. Since then it would be a contradiction and every possible sentence could be derived from it.

The separation stops the theory U from being contradictory.

Anonymous at 6:27 AM on December 22, 2016 | #8016 | reply | quote

There is a further problem which is solved in the above way, I mentioned. Which is you could say that U is a theory which contains R, which is a new theory, created from the subset of true statements of T, in this way U does not contain T and -T. Because it does not contain T. but it does contain, say, an explanation of the test report, p, which is equivalent to ~r, where r, is the prediction from T, which turned out to be false.

Anonymous at 6:48 AM on December 22, 2016 | #8017 | reply | quote

>I think A, B, C, D, E, F, G are theories.

>And B could refute A.

Yes, but this contains the implicit assumption that all of these theories are seperate - it is a conjecture about the theories. A theory we use for prediction is not a theory about theories, but a theory about the way the world works. You would not use the theories as though they were one theory that makes predictions. You would seperate them.

Anonymous at 7:04 AM on December 22, 2016 | #8018 | reply | quote

Furthermore there is a distinct difference between

The theory that A, B, C, D, E, F, G are theories.

Since this theory contains the 7 existential statements. It just says there exists 7 theories. It does not contain those theories. It contains "there exists a theory A" etc. This theory is unrefutable.

If your theory only asserted the existence of the 3 elements that you say a part of it, it too would be an irefutable theory.

Anonymous at 8:02 AM on December 22, 2016 | #8019 | reply | quote

> > > My contention here, is that the explanation of the boundary is outside the theory.

> > what problem are you trying to solve by this separation?

> It avoids U being contradictory.

i think you dropped the context, then misunderstood what "this" refers to. the separation in question is "the explanation of the boundary is outside the theory". you don't talk about that in your answer.

this seems like you don't understand how quotations work. you didn't read my reply sentence *as a reply to the text i quoted immediately before it*, and just made a wild guess at what it had to do with.

since you don't seem to understand the basics of reading and replying in a conversation, would you be interested in learning about that and trying to become a more competent thinker and discusser? is that a project that interests you? if not, why not?

Anonymous at 2:21 PM on December 22, 2016 | #8022 | reply | quote

Theory Q: "There exists a theory A and it consists of [the full contents of theory A go here]. There exists a theory B and it consists of [full contents of B here]. [etc]"

contradictory theories A and B can both be contained in Q, like this. you seem to interpreting the counter example in a hostile way that doesn't make my point when it's easy to interpret in a way that makes my point. This way they are not both asserted by Q, but are contained.

you seem confused and seem to be refusing to reply about lots of the problems that come up in the discussion, like your mistaken claim that you didn't say "contain[s]" first. when you're making mistakes and then try to press on anyway while silently ignoring all replies about your mistakes, that's super irrational.

Anonymous at 2:25 PM on December 22, 2016 | #8023 | reply | quote

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