No observation rules this belief out. It is ruled out by logic, it doesn't require any observation at all. — Isaac

But other (background) beliefs would compel us to interpret our observations (i.e. laden them with the theory contained in those beliefs) as demonstrating that self-contradictory belief to be so. Since a self-contradictory belief cannot be so — which we already knew, yes — we cannot within contradiction maintain those beliefs according to which our our observations demonstrate the contradictory belief to be true.

You keep saying I’m just repeating claims, but I’m repeating parts you apparently didn’t read, since they’re already addressing the criticisms you yourself are repeating.

If we ignored the potential fallibility of our background beliefs, an observation that is contrary (as interpreted by those background beliefs) to the particular belief we’re aiming to test would straightforwardly falsify that belief. That’s dogmatic falsificationism. Confirmation holism rightly points out in response to that that those background beliefs through which we’re interpreting our observations are themselves as subject to revision as the belief we’re aiming to test.

But that still leaves you with an observation that your background beliefs plus the theory under consideration together say should be impossible — logically impossibly, in conjunction with all those beliefs. All those beliefs and the thing they would have you say you observed cannot all be true at once. So, given that you did certainly observe something or other, you’ve either got to straightforwardly follow the implications of that observation (as interpreted through your background beliefs) on the falsity of the theory under consideration, or change something else about those background beliefs to allow you to reinterpret your observation as something else that doesn’t falsify the theory in question.

Either way, the observation of something your beliefs say should be logically impossible compels the revision of some beliefs or others to avoiding having to conclude that you observed something logically impossible.

But other (background) beliefs would compel us to interpret our observations (i.e. laden them with the theory contained in those beliefs) as demonstrating that self-contradictory belief to be so. Since a self-contradictory belief cannot be so — which we already knew, yes — we cannot within contradiction maintain those beliefs according to which our our observations demonstrate the contradictory belief to be true. — Pfhorrest

But they don't "demonstrate the contradictory belief to be true". Observations don't demonstrate any belief to be either true or false, they underdetermine.

Try it in these terms...

Belief A is a belief about logic {X and ~Y, where X implies Y, is inconsistent}.
Belief B is an inductive belief {that X implies Y}
Belief C is a belief in an observation {that I just observed X and also ~Y}.

Resulting from C one could believe ~C, ~B, or ~A. One cannot believe A, B, and C. But we knew this all along. Prior to C, one could believe A and B. After C, one could believe A and B. C hasn't changed anything

But that still leaves you with an observation that your background beliefs plus the theory under consideration together say should be impossible — logically impossibly, in conjunction with all those beliefs. All those beliefs and the thing they would have you say you observed cannot all be true at once...

...Either way, the observation of something your beliefs say should be logically impossible compels the revision of some beliefs or others to avoiding having to conclude that you observed something logically impossible. — Pfhorrest

Not with sufficient additional beliefs about C, and additional beliefs don't falsify anything.

Going from believing A+B to believing A+B+C+D hasn't falsified A, B, C, or D has it?

Observations don't demonstrate any belief to be either true or false, they underdetermine. — Isaac

They underdetermine precisely because they are theory-laden and those theories with which they are laden can always be changed to change what the observation is taken to mean. Changing those theories to reinterpret the observation in a way that doesn’t falsify the theory you’re trying to test is still changing what theories you believe in response to observation. That you have a choice of which theories to change doesn’t undermine that.

Try it in these terms...

Belief A is a belief about logic {X and ~Y, where X implies Y, is inconsistent}.
Belief B is an inductive belief {that X implies Y}
Belief C is a belief in an observation {that I just observed X and also ~Y}.

Resulting from C one could believe ~C, ~B, or ~A. One cannot believe A, B, and C. But we knew this all along. Prior to C, one could believe A and B. After C, one could believe A and B. C hasn't changed anything — Isaac

Belief C hinges on the theories with which the observation is laden. If you reject C, then you have to change those beliefs that would otherwise lead you to conclude that C. If you accept C, then you have to reject B (or A, but if we’re getting into the realm of possibly rejecting logical entailments then we’re free to be wildly inconsistent and not reject anything; all this is premised on caring about logical consistency).

In any case, you have to reject some beliefs you already had: either throw out B (the obvious first choice), throw out some part of the background beliefs that lead you to believe C (probably a much taller order), or throw out A (if you just want to give up on logical consistency entirely).

Not with sufficient additional beliefs about C, and additional beliefs don't falsify anything. — Isaac

If you have to add additional beliefs to hang on to your belief system — your belief system cannot retain consistency with your experience without adding those other beliefs —then you have falsified the negations of those beliefs. You still had to change something about your belief system, because the belief system exactly as you had it before proved irreconcilably with observation, i.e. it was falsified.

You're presenting an overly simplistic account of verification and falsification, by applying the abstracted logic of deduction to inductive reasoning. When we conjecture that if some hypothesis were true, then we would expect to observe whatever is predicted by the hypothesis, this is not a straightforward 'If A then B' where not-B guarantees that A is not the case. In deductive reasoning affirming the consequent is a fallacy, but not so in the process of inductive reasoning.

Here's an example that might make it clearer to you: say the hypothesis is that evolution has occurred; if that were true we might expect to see fossil remains that show structural similarities that we could take to support that conjecture. If we don't see fossil remains that show such a development that does not falsify the hypothesis of evolution definitively, because the fossils may have been destroyed by processes of which we are not aware.

To put it another way, if 'evolution then fossils with commonalities of structure in different species' can just as well be reversed: 'if fossils with commonalities of structure in different species then evolution'. This reversal would be a fallacy in deductive reasoning but not so in inductive reasoning. Of course there is no logical entailment in either of these inductive conjectures.

applying the abstracted logic of deduction to inductive reasoning — Janus

The whole point is that inductive reasoning is not valid. No number of observations of the consequent of an implication can tell you that the antecedent of it is true. It's invalid for one case, and it's still invalid after a million cases.

If all swans are white, then this swan will be white... this swan is white, therefore all swans are white? Of course not, but that swan is also white, and that one too, I've seen a million white swans, so clearly all swans must be white, no? Oh look, here's that new bird from Australia... (Also: here's a green leaf... and a million other green leaves. "All swans are white" = "All non-white things are non-swans", and a green leaf is a non-white non-swan, so a million green leaves proves that all swans are white... no?)

OTOH even a single observation of the negation of the consequent validly tells you the antecedent is false.

The thing is, the antecedent is more complicated than you'd initially assume, a la:

If we don't see fossil remains that show such a development that does not falsify the hypothesis of evolution definitively, because the fossils may have been destroyed by processes of which we are not aware. — Janus

This is the underdetermination and theory-laden-ness that Isaac and Banno keep harping on, which is completely correct, but is not a point against falsificationism. It's not so simple that "if evolution then fossils"; it's actually "if evolution and a bunch of other assumptions then fossils". Not seeing fossils doesn't necessarily falsify evolution, but it falsifies something; if you don't reject evolution, then you have to reject some of those assumptions that would lead you to expect to never have evolution with no fossils, and in either case you're rejected something you believed on account of evidence that was contrary to the conjunction of all your beliefs.

Formally, you've got "if (A and B and C and ...) then Z", and "not-Z", therefore "not (A and B and C and ...)" or equivalently "not-A or not-B or not-C or ...".

The whole point is that inductive reasoning is not valid. No number of observations of the consequent of an implication can tell you that the antecedent of it is true. It's invalid for one case, and it's still invalid after a million cases. — Pfhorrest

When it comes to science inductive and abductive reasoning is all we have. My point has been that there is no real difference in inductive and abductive reasoning between verification and falsification; insofar as neither verification nor falsification are deductively certain, ;logically entailed. And that is why I say it is oversimplifying and misleading to present them as being logically the same as modus ponens and modus tollens respectively.

Also, the point about the whole network of knowledge being in play is well taken against oversimplifying the issue I think.

When it comes to science inductive and abductive reasoning is all we have. — Janus

On a justificationist account, sure.

The critical rationalist / falsificationist account is aiming precisely to rectify that problem.

Induction is fine as a way of generating hypotheses, by identifying patterns in observations. But then when it comes to seeing if those hypotheses really work out, finding out if they're really true, seeing that the pattern you suspects always holds has continued to hold so far doesn't really tell you much of use.

That last sentence reminds me of a great little video that turns out to be about exactly this subject:

The critical rationalist / falsificationist account is aiming precisely to rectify that problem. — Pfhorrest

I don't see how it can do that when it necessarily relies on the inductive assumptions that have been codified as the so-called laws of nature. If nature were not assumed to be invariant, then all of science would be utterly at sea; and I can't see how falsification could help with that, because the compass is always abductive reasoning based on induction (the expectation that the law-like behavior of things will remain as it has been found to be). Falsification can never be definitive, any more than verification can. How much less definitive would it be if there were no inductive assumption that the laws of nature cannot change?

When it comes to simple observation claims I agree that verification and falsification do appear different. But again they can be reversed to make verification and falsification logically equivalent. So, I could assert "Not all swans are white", and the observation of a black swan would verify this claim just as it falsifies the obverse claim "No swans are white".

PS. Cute video! I got the rule before the participants, but it took a little while.

I don't see how it can do that when it necessarily relies on the inductive assumptions that have been codified as the so-called laws of nature. If nature were not assumed to be invariant, then all of science would be utterly at sea; and I can't see how falsification could help with that, because the compass is always abductive reasoning based on induction (the expectation that the law-like behavior of things will remain as it has been found to be). Falsification can never be definitive, any more than verification can. How much less definitive would it be if there were no inductive assumption that the laws of nature cannot change? — Janus

Assuming that there are some invariant laws of nature or another is not itself induction. Only seeing a lot of examples of a pattern and taking that as evidence that that pattern is an invariant law of nature is. Falsificationist methods still look for invariant laws of nature, but rather than inductively inferring them, they try to find bounds on what they could be. That's what the video demonstrates: finding examples of your hypothesis being right doesn't tell you anything. Finding out what hypotheses are wrong tells you something useful.

But again they can be reversed to make verification and falsification logically equivalent. So, I could assert "Not all swans are white", and the observation of a black swan would verify this claim just as it falsifies the obverse claim "No swans are white". — Janus

The observation of a black swan would falsify that all swans are white and whatever background assumptions, which does indeed then entail that not all swans are white or some of those background assumptions are false; but that's just because "there exists a non-white swan" is logically equivalent to "not all swans are white", so if there seems to be a non-white swan then either there is indeed a non-white swan or some of your assumptions through which you're interpreting the apparent observation of a non-white swan are false.

The observation of a black swan would tell you nothing at all about whether "no swans are white". Just flip it around for the obvious counterexample: medieval Europeans would have claimed that no swans were black, and looking around to see lots of white swans... would not confirm that, because they always might, and eventually would, come across some black swans anyway. There being no white swans doesn't even demand that there be any black swans... there could be no swans. It's true that there are no pink unicorns, not because there are lots of blue unicorns, but because there are no unicorns at all.

Assuming that there are some invariant laws of nature or another is not itself induction. Only seeing a lot of examples of a pattern and taking that as evidence that that pattern is an invariant law of nature is. — Pfhorrest

We assume that the laws of nature are invariant because all our observations to date verify that they have been. Or obversely, you can say that none of our observations have falsified that they have been. The assumption that they will be invariant in the future is simply an expectation that we share with the animals; the habit of thinking that things will be as they have been. The point here is that verification is nothing more than lack of falsification, and vice versa; they are two sides of the one inductive coin; and neither of them definitive.

The observation of a black swan would tell you nothing at all about whether "no swans are white". — Pfhorrest

Sorry, that wasn't as I intended ; it should have been "So, I could assert "Not all swans are white", and the observation of a black swan would verify this claim just as it falsifies the obverse claim "All swans are white".

Changing those theories to reinterpret the observation in a way that doesn’t falsify the theory you’re trying to test is still changing what theories you believe in response to observation. — Pfhorrest

It is. Your claim is the ability to falsify them, not change them around.

Belief C hinges on the theories with which the observation is laden. If you reject C, then you have to change those beliefs that would otherwise lead you to conclude that C. — Pfhorrest

No, as I said below, usually all that's needed is additional beliefs - no changes required.

if we’re getting into the realm of possibly rejecting logical entailments then we’re free to be wildly inconsistent and not reject anything; all this is premised on caring about logical consistency — Pfhorrest

Great, glad we agree there, if we can drop ~A as an option, it makes discussing the example simpler.

In any case, you have to reject some beliefs you already had: either throw out B (the obvious first choice), throw out some part of the background beliefs that lead you to believe C (probably a much taller order) — Pfhorrest

a) Why is throwing out C a much taller order? In the vast majority of complex cases, the idea that our observations are incorrect is the most go-to answer to any inconsistencies. We can't even trust our observations with the simplest of matters (see optical illusions), so when it comes to interpreting complex scientific experiments, rejecting C is the number one choice.

b) More importantly, you're doing your old trick of completely ignoring the bits of the counter argument you don't like. I've just explained how there's no need to reject C, one usually adds beliefs to C, such as the example Srap gave (we are seeing these signals on the device, but additionally we believe there's some dirt on the dish, that would explain them). They weren't entertaining the idea that the readings they saw were illusionary, only that, the world contained a reason for them that they did not currently know - an additional belief.

If you have to add additional beliefs to hang on to your belief system — your belief system cannot retain consistency with your experience without adding those other beliefs —then you have falsified the negations of those beliefs. — Pfhorrest

Which is, I believe, what @Janus is trying to explain. You can't just claim falsification by subsuming falsifying the negation of a belief. That's argument by re-definition of the terms. How is falsifying ~D different from verifying D? D and ~D exhaust the set. By your own examples of the difference it's evidently not true that you have falsified ~D by requiring D to shore up your belief systems. E might have done the same job, or F, or G. The fact that D happens to work as an additional belief to make observation C fit with belief B does not in any logical sense imply we have falsified ~D. Having claimed to understand underdetermination, you then proceed to presume it doesn't exist at every new turn of your argument. The additional beliefs which allows C+B is underdetermined by the range of available additional beliefs which would do that job.

It is. Your claim is the ability to falsify them, not change them around. — Isaac

Being epistemically compelled to change beliefs just is falsifying them. It feels like you're being intentionally obtuse here. If you can't (without inconsistency) keep believing things exactly like you believed them before, but have to make some change to what you believe, then the conjunction of the things you believed before has been falsified. To insist that it has to be one particular belief that you were specifically setting out to test that is falsified in order for it to count as falsification is to argue against the strawman of dogmatic falsification.

It really seems like we're getting into a stupid argument over what does or doesn't count as "falsification", when that's not even the main label I apply to my views; I only mention it as another name more commonly given to them, even narrower than "critical rationalism", which I what I started out talking about in the other thread, so as not to bring my specific epistemological framework into it too much. The unique thing about critical rationalism / falsificationism that my view shares is the principle I call "liberalism", which says to go ahead and hold beliefs even if you can't prove them conclusively.

But the aspect of my view you seem to be arguing against is the one I call "criticism", which is a disambiguated subtype of the broader category commonly called "skepticism" (as @Kenosha Kid called it earlier) or "rationalism" generally. It's just the negation of fideism, where that in turn is the claim that some beliefs are beyond question, beyond refutation, unable to possibly be shown false or incorrect or wrong. You seem to be taking the even further stance that all beliefs are like that, which really surprises me coming from you, because I had you figured for the hard-science irreligious type, but now you seem to be saying "everyone can just believe whatever they like and there's no figuring out who's right or wrong". (Including, because you're jumped on this strawman before too, any less boolean degrees of rightness or wrongness, not just some black-and-white absolutism).

No, as I said below, usually all that's needed is additional beliefs - no changes required. — Isaac

Adding a belief to your set of beliefs is changing that set of beliefs, and as above, if you're epistemically compelled to make that change, that's the same thing as that set of beliefs being falsified.

a) Why is throwing out C a much taller order? In the vast majority of complex cases, the idea that our observations are incorrect is the most go-to answer to any inconsistencies. We can't even trust our observations with the simplest of matters (see optical illusions), so when it comes to interpreting complex scientific experiments, rejecting C is the number one choice. — Isaac

This is a good point. I was imagining the rain dance example scenario, where "throwing out C" means positing invisible rain, not the radio telescope example scenario, where "throwing out C" means positing dirt on the dish. I did only say that throwing out C was "probably", not "necessarily", a taller order, but yes, which revision to your beliefs is a bigger, less pragmatic hassle will vary from scenario to scenario.

b) More importantly, you're doing your old trick of completely ignoring the bits of the counter argument you don't like. — Isaac

You mean the parts I've already given counter-counter-arguments to? Yeah, I don't proceed on the assumption that something I just showed false was actually true.

I've just explained how there's no need to reject C, one usually adds beliefs to C — Isaac

And I've just explained how adding to C is changing C, and changing away from something just is rejecting it.

In Srap's example, "C" is the set of all of the background assumptions made when first making the observation, which include that the dish is clear of debris. Upon seeing an unexpected signal, a possible revision to the beliefs to account for that is "maybe there is dirt on the dish". Because "there is no dirt on the dish" was one of the beliefs within C, positing that maybe there is dirt on the dish is a change to C, a change away from the old C to some new set of background assumptions very much like C but different in whether there is thought to be dirt on the dish. That constitutes a rejection of C.

(Of course, in the actual case of Srap's example, that replacement for C in turn was quickly falsified itself, as the observations expected from the hypothesis that there is not dirt on the dish soon failed to materialize, when they didn't see any dirt on the dish. Sure, they could have still hypothesized invisible dirt instead of abandoning that hypothesis, but supposing there's a CMB was less of a huge change to the accepted view than everything that would be required to suppose there's invisible dirt on the dish).

The additional beliefs which allows C+B is underdetermined by the range of available additional beliefs which would do that job. — Isaac

Yet nevertheless additional beliefs are required, which constitutes a change away from the previous set of beliefs, which constitutes a rejection of that set of beliefs as it was. That the new set of beliefs is very similar to the old one doesn't make a difference.

Adding a belief to your set of beliefs is changing that set of beliefs, and as above, if you're epistemically compelled to make that change, that's the same thing as that set of beliefs being falsified. — Pfhorrest

Yet...

's just the negation of fideism, where that in turn is the claim that some beliefs are beyond question, beyond refutation, unable to possibly be shown false or incorrect or wrong. — Pfhorrest

So, what is it you imagine the fideist thinks in our scenario that is different from the critical rationalism you espouse? They believe A. They believe B, they believe C (which logically contradicts B without some additional beliefs - ie contradicts A). What then? Using a real example, what does this mythical fideist then think?

They're not allowed to explain C away using any revisions or further beliefs, because that's just 'critical rationalism' apparently. So they must literally believe two contradictory things with no reason as to why, despite also believing it is impossible for two contradictory beliefs to coexist.

Who are these people? Examples please.

So, what is it you imagine the fideist thinks in our scenario that is different from the critical rationalism you espouse? They believe A. They believe B, they believe C (which logically contradicts B without some additional beliefs - ie contradicts A). What then? Using a real example, what does this mythical fideist then think? — Isaac

A fideist thinks at least one of their beliefs is not subject to question. In any of the A-B-C scenarios we've been discussing, they hopefully will admit to A (not be explicitly logically inconsistent), and probably have some B that they hold immune to question, and so will resort to revising C.

Take for concrete examples any tortured argument that some evidence that seems to disprove a religious belief isn't really the evidence it seems to be because [convoluted excuses]. Or substitute "religious belief" with "conspiracy theory"; the pattern is the same. Anyone who clings to some particular belief with unreasonable tenacity and will jump through whatever mental hoops necessary to excuse or dismiss any evidence that would otherwise apparently disprove it.

They're not allowed to explain C away using any revisions or further beliefs, because that's just 'critical rationalism' apparently. — Isaac

No, they are allowed to explain away the observations by revising C. That's something that critical rationalism has in common with fideism, and different from justificationism, not something unique to critical rationalism. I've only been arguing against your apparent claim that critical rationalism cannot do that and still be critical rationalism, not that that is something only critical rationalism can do.

Fideism shares the "liberalism" part of my "critical liberalism"*, but it negates the "criticism" part of it: the fideist agrees with me that you are free to hold beliefs without proving them first, but also thinks that you may hold beliefs as utterly beyond disproof.

What I term "cynicism" (comprised mostly of justificationism minus that parts that jump ship to fideism) instead shares the "criticism" part with me, but negates the "liberalism" part: the "cynic" agrees with me that everything is subject to questioning and might be disproven, but also thinks that you have to conclusively prove anything before it's okay to believe it.

*(The term "critical rationalism" is not "criticism + rationalism" in the same way that my term "critical liberalism" is "criticism + liberalism", even though they mean the same thing. Instead, it's "rationalism inasmuch as it it critical, but not inasmuch as it is 'cynical'", where "not 'cynical'" is precisely the thing that I mean by "liberal").

In any of the A-B-C scenarios we've been discussing, they hopefully will admit to A (not be explicitly logically inconsistent), and probably have some B that they hold immune to question, and so will resort to revising C. — Pfhorrest

So how do you, in practice, distinguish such thinking from the critical rationalist scientist who, we've just established, is more than likely to pick C to revise also? Is there some psychological test of one's intention behind choosing C to revise?

Anyone who clings to some particular belief with unreasonable tenacity and will jump through whatever mental hoops necessary to excuse or dismiss any evidence that would otherwise apparently disprove it. — Pfhorrest

How are you determining "unreasonable tenacity"? We've just established revising C is a perfectly reasonable option, so you can't judge it simply on a preference for revising C.

Again, you've failed to provide the asked for examples. What we need to go through is a concrete example of a fideist refusing to revise B in the light of C where it is 'unreasonable' of them to do so, as compared to a critical rationalist deciding not to revise B, but rather revise C and it being 'reasonable' of them to do so. Otherwise you're at risk of arguing against a straw man version of fideism.

Underlining your model here, just as in your meta-ethic, is an unwritten clause that you personally get to be the final arbiter. Here, we can't distinguish between the fideist rejection of C and the rationalist rejection of C without drawing on your personal subjective judgement of what is 'reasonable tenacity' and what isn't.

We can’t necessarily tell what epistemological method someone else is using in the third person. We can plausibly guess at it, judging from their discursive behavior, but of course we can’t actually read other people’s minds and see whether they are willing to revise B and just find revising C more plausible, or if they hold B as beyond question.

That doesn’t mean we can’t discuss the merits of using different methods ourselves in the first person. Which is all I do in my arguments for my methodology: illustrate why doing things otherwise is more likely to lead you into or keep your in error than this way, so it’s in your interest, if you care about figuring out the truth, to do it this way. It’s not all about judging other people.

Fideism shares the "liberalism" part of my "critical liberalism"*, but it negates the "criticism" part of it: the fideist agrees with me that you are free to hold beliefs without proving them first, but also thinks that you may hold beliefs as utterly beyond disproof. — Pfhorrest

Fideism proper really only applies to beliefs that are unverifiable. Such beliefs are obviously also unfalsifiable, since verification and falsification are just two sides of the one (non-definitive) coin. Belief in God, Karma or rebirth are examples.

In practice we are all fideistic, insofar as we all believe things we have no hope of personally confirming or dis-confirming. The vast bulk of what every person takes for granted falls into this category. The only difference between this practical everyday fideism and fideism proper is that the things believed in the former case may be confirmed or disconfirmed in principle, if not in practice.

Fideism proper really only applies to beliefs that are unverifiable. Such beliefs are obviously also unfalsifiable, — Janus

Yes, I call that “transcendentalism” and reject it precisely because it demands fideism. I considered mentioning that in my response to Isaac just above, because that is a circumstance where you can be sure someone is using fideism since there is no alternative then, but I decided not to complicate things.

Well, I'm going to complicate things by suggesting that insofar as philosophical claims are neither verifiable nor falsifiable, philosophy itself also falls into the fideism proper category.

On my account philosophical claims are not properly claims about what is or isn't real to begin with, and so are not the kind of claims that are made true or false by empirical observation. Other kinds of claims that are not about what is or isn't real -- like philosophical claims, logical/mathematical claims, and moral claims -- can be tested by means other than empirical observation, and so do not necessarily demand fideism. (There are still some such claims that are held to be beyond any testing, and those kinds of claims do demand fideism, and for that reason I am also against them, but all philosophical claims don't fall into that category).

Other kinds of claims that are not about what is or isn't real -- like philosophical claims, logical/mathematical claims, and moral claims -- can be tested by means other than empirical observation, and so do not necessarily demand fideism. — Pfhorrest

I see logical/mathematical propositions as being essentially different than philosophical and moral claims inasmuch as their rule-governed truth or falsity is intuitively self-evident to the unbiased observer (given they have acquired the requisite expertise). In other words when it comes to logical and mathematical propositions there are definitive rule-based correct and incorrect answers.

It seems obvious that philosophy is not like this, and the history of philosophical ideas confirms that; there is widespread disagreement among the experts. There may be near universal agreement about moral principles concerning certain extreme acts like murder, rape, child abuse and so on; but I think this is likely underpinned by what might be called "normal" human faculties for compassion and empathy, as well as the inevitable social conditioning that comes with the pragmatic need to proscribe anti-social acts, particularly the more egregious ones.

In Srap's example, "C" is the set of all of the background assumptions made when first making the observation, which include that the dish is clear of debris. Upon seeing an unexpected signal, a possible revision to the beliefs to account for that is "maybe there is dirt on the dish". Because "there is no dirt on the dish" was one of the beliefs within C, positing that maybe there is dirt on the dish is a change to C, a change away from the old C to some new set of background assumptions very much like C but different in whether there is thought to be dirt on the dish. That constitutes a rejection of C.

(Of course, in the actual case of Srap's example, that replacement for C in turn was quickly falsified itself, as the observations expected from the hypothesis that there is not dirt on the dish soon failed to materialize, when they didn't see any dirt on the dish. Sure, they could have still hypothesized invisible dirt instead of abandoning that hypothesis, but supposing there's a CMB was less of a huge change to the accepted view than everything that would be required to suppose there's invisible dirt on the dish). — Pfhorrest

This might be the right point to confront something @Isaac is always reminding us about: the stories we tell about our beliefs are post-hoc. They are rationalizations. That needn't mean they are bad or untrustworthy or invalid or indefensible, but it's worth bearing in mind.

What is the situation when our boys "switch on" the radio telescope? What "set of beliefs" do they hold? There's no reason to think they believe there are no pigeons nesting in the antenna; I believe they discovered them when they checked the antenna, and they thought this explained their results. Do they hold some more general belief that they antenna is unobstructed? I don't know, and I doubt you do either. So far as I can tell, they would have no reason to hold a belief either way about it being obstructed. They probably observed its construction or installation, and would have memories of seeing at that time that it was unobstructed; does that mean they held a continuing belief that it continued to be unobstructed? I doubt it, but we'll come back to this in a minute. (Btw, pictures show the radio telescope not to be on the roof and not exactly a dish either, both mistakes of mine.)

Similar remarks about the equipment in the lab: did they hold a belief that it was all in working order? More likely, but again there's a temporal issue: did they believe it was a-ok as they got the readings that puzzled them? Surely, else they wouldn't have been taking readings. Maybe in preparation for taking first readings, they did some tests. What if they didn't? If you grab a jug of milk out of the fridge, do you hold a belief that it won't split open? What about a belief that a hole won't spontaneously appear in the bottom?

We're accustomed sometimes when doing philosophy to talk about "belief" this way, as a sort of abstract mental correlate of the actions we take. (I have defended talking this way on this very forum.) Sitting "implies", in some sense, a belief that the chair will hold our weight, that it's real not an illusion, that it won't turn out to be made of some other material than it appears to be, that it won't spontaneously move or even disappear, and so on.

One reason this attribution of belief feels okay is our experience of finding that an assumption we've made was incorrect. But what does that mean exactly? What is an assumption like? An awful lot of assumptions, including the ones that turn out to be incorrect, are not held explicitly; does it help to describe them as being held implicitly? Some we might be inclined to attribute to people in order to make sense of their behavior; if you fish a coin out of your pocket and put it into a vending machine, you must be assuming the coin is legal tender the machine won't reject. You're not holding such a belief explicitly, but you're assuming it's the case, and even that only implicitly.

How does that actually help us? Suppose the coin is accepted; does that justify our assumption that it was legal tender? There's no logical reason not to say that, I don't think, but it's not the first thing I'd reach for in describing the situation. What if it's rejected? We try again, and it's rejected again -- sometimes they just don't quite catch right. What would you do next? You'd have a close look at the coin. Is it damaged? No. Maybe it's fake, doesn't have the right weight.

What's going on here? Have you found out you must reject your belief that the coin was genuine? Maybe, kinda. But when did that happen? And how? You expected the coin to just work, that much is clear; when it didn't, you could shrug it off and try another coin (vending machines are a little unpredictable) and never think about it, or you could look for an explanation.

I suspect cases where the natural next step to take is the logical analysis of the set of beliefs you held right at the moment when things started going wrong are pretty rare overall. The natural step is often going to be investigating, at least a little, looking at stuff. And some theorizing, or hypothesizing. I think this is the moment where you might identify an assumption that the coin is genuine, but only because it is now suddenly in question whether that's true. In other words, it might occur to you (or not) that the coin being fake would cause the machine to reject it. "The coin is not genuine" would appear in your world not as the negation of some belief you actually held, implicitly, but as an hypothesis that could explain why it was rejected. Implicit assumptions seem generally to show up this way -- not in themselves, and not in the form we are claimed to have held them, but negated, when the converse might be the explanation we need.

So in Holmdel, New Jersey, did Penzias and Wilson assume the equipment was still working having checked it out at some earlier time? Why not just say that it occurred to them that a malfunction might cause the readings they were getting. Did they assume nothing was obstructing the antenna? In particular that there were no pigeon nests in it? Of course not. But it might occur to them that some kind of obstruction might cause the results they got.

You can patch these things together after the fact into a logical structure -- we're really, really good at rationalizing, but so what? I hope it's clear, I'm not trying to reform how we talk about assumptions and so on, but I do think trying to formalize this way of speaking into a logical system that allegedly explains how people come to believe what they do or how they change what they believe -- it's a mistake. I think its mistakenness shows up in part in its inability even to do what it claims -- eliminate false beliefs. It also fails to account for the fact that investigating actually works -- it shouldn't, because you can always just reject the new observation, or you can find some way to take it on-board without falsifying anything, always.

That's my sense of things. I think the whole approach (and it used to be mine too) is a mistake, just the wrong way to think about beliefs.

On the whole I have no real objections to any of this. I do think it's not really an argument against anything I've been saying, because I'm not claiming that the background beliefs in discussion are explicitly held -- that's precisely what makes them "background", that they're assumptions it didn't even occur to us that we had taken any position about until something we didn't expect happens and we're pressed to explain what exactly about our expectations was in error.

It also fails to account for the fact that investigating actually works -- it shouldn't, because you can always just reject the new observation, or you can find some way to take it on-board without falsifying anything, always. — Srap Tasmaner

I think the reason for that is that the adjustments that must be made to consistently accommodate the new observation without falsifying the most obvious thing it would falsify (the thing you nevertheless want to continue believing it) quickly become more and more unwieldy.

"Strange radio signal? Maybe it's an equipment error. No. Maybe it's something on the dish. Pigeons were on the dish, now they're not, so that fixed it? No. Maybe something else is still on the dish. There was dirt on the dish, now there's not, so that fixed it? No. Maybe there's... invisible dirt on the dish? No, that's too far-fetched (would require modifying too many other assumptions). So maybe there is a real radio signal. Is it coming from other terrestrial sources? No. Other astronomical sources? No. Could there be... invisible sources? That's almost as far-fetched as invisible dirt. (But lets check anyway... nope). So maybe there really is a microwave-frequency signal coming from all directions? Well it looks like it's either that or something like invisible dirt, and as weird as some cosmic microwave background radiation is, that's less weird (requires modifying fewer other assumptions) than invisible dirt."

"Strange radio signal? Maybe it's an equipment error. No. Maybe it's something on the dish. Pigeons were on the dish, now they're not, so that fixed it? No. Maybe something else is still on the dish. There was dirt on the dish, now there's not, so that fixed it? No. Maybe there's... invisible dirt on the dish? No, that's too far-fetched (would require modifying too many other assumptions). So maybe there is a real radio signal. Is it coming from other terrestrial sources? No. Other astronomical sources? No. Could there be... invisible sources? That's almost as far-fetched as invisible dirt. (But lets check anyway... nope). So maybe there really is a microwave-frequency signal coming from all directions? Well it looks like it's either that or something like invisible dirt, and as weird as some cosmic microwave background radiation is, that's less weird (required modifying fewer other assumptions) than invisible dirt." — Pfhorrest

On what grounds do we judge things to be "far-fetched" if not on the basis of inductively formed beliefs or attitudes which are adopted implicitly or explicitly, or else simply believing some "official" story which is itself in the final analysis purportedly based on inductive confirmation? You won't be able to eliminate inductive thinking as easily as you apparently think you will.

far-fetched (would require modifying too many other assumptions). — Pfhorrest

less weird (requires modifying fewer other assumptions) — Pfhorrest

But more than the amount of modifications, it's about the amount of exceptions to an otherwise more parsimonious system of beliefs. If you have the choice between a parsimonious system plus a huge mountain of exceptions, or a slightly less parsimonious system that's still more parsimonious than the other plus its mountain of exceptions, it's pragmatically more useful to go with the latter.

If we didn't care about parsimony at all, we could always just hold a belief system that consists of an unorganized list of all of the uninterpreted particulars of every experience we've ever had, but that wouldn't mean anything to us, it wouldn't show us any connections between things or highlight any patterns in any way that allows us to usefully interact with the source of those experiences. The whole reason to form theories at all instead of just keeping unorganized lists of experiential minutia is to have that easier-to-use, more-parsimonious abstraction to work with, so it's counterproductive to pick a less-parsimonious explanation when a more-parsimonious one that equally fits the experiences is available.

That's all fine, but you're not dealing with the fact that all the assumptions we hold are based on either induction or authority; with the latter being based ultimately on induction. So the thing I was critiquing was your claim to be able to do without induction.

I said already earlier that induction is a perfectly fine way of coming to your initial beliefs -- not that you need any reason to believe anything, rationally speaking, on my account, but in light of that, induction is as good of one as any.

My only point about induction is that it doesn't prove anything. If you induce from a pattern of white swans that all swans are white, and someone else disagrees, pointing to more white swans doesn't rationally settle that argument, i.e. it doesn't show that you're right and they're wrong, or even that you're more likely to be right and they're more likely to be wrong. (Consider the possibility that they're from Australia and know firsthand that there are black swans; no number of white swans you show them will matter at all to them.)

That doesn’t mean we can’t discuss the merits of using different methods ourselves in the first person. Which is all I do in my arguments for my methodology: illustrate why doing things otherwise is more likely to lead you into or keep your in error than this way, so it’s in your interest, if you care about figuring out the truth, to do it this way. It’s not all about judging other people. — Pfhorrest

In order to advocate it you must at least have judged that there exist people which do not follow this method, otherwise it's like advocating breathing. So it is implicitly, very much about judging other people, especially as you've advocated this method on a board dedicated to the discussion of philosophy, not class of primary school children whom you might prima facie suspect of benefiting from guidance.

No. It's very much about judging other people.

The point here is that you cannot get out of your 'algorithmic' method without resorting to subjective judgements of

unreasonable — Pfhorrest

plausible — Pfhorrest

obvious — Pfhorrest

unwieldy — Pfhorrest

So you cannot dismiss anyone's though process without that dismissal simply being grounded on the fact that you personally find their revision of C (rather than revision of B) to be 'unreasonable' in the circumstances - yet you've given no account at all of how you justify that assessment.

In order to advocate it you must at least have judged that there exist people which do not follow this method — Isaac

We can of course know when they tell us, but that's not the scenario you asked about; you asked how we can tell. There are plenty of people who tell us that they use (and advocate the use of) fideistic methodologies; basically all of "Reformed epistemology" is about that. See for contemporary examples William Lane Craig or Alvin Plantinga.

you've advocated this method on a board dedicated to the discussion of philosophy, not class of primary school children whom you might prima facie suspect of benefiting from guidance. — Isaac

You always seem to forget that I consider all of the philosophy I'm advocating to be a shoring-up of common sense against badly done philosophy. I'm not trying to say that ordinary people all do things wrong and here's the secret way to do it right. I'm trying to explicate what is right about the way most people usually do things, and identify the kinds of deviations from that that can lead to ludicrous philosophical nonsense.

So you cannot dismiss anyone's though process without that dismissal simply being grounded on the fact that you personally find their revision of C (rather than revision of B) to be 'unreasonable' in the circumstances - yet you've given no account at all of how you justify that assessment. — Isaac

See the several preceding posts where I discuss parsimony as the rationale behind things like "unwieldy". The rest of those quote snips are either explicitly describing someone else's subjective judgement, or speaking loosely in conversation (assuming that we have some common ground in our casual, on-the-ground opinions, that I can refer to, despite our disagreement on technical philosophical things) and not as part of explicitly defining my philosophical position.

The more you write the more convinced I become that you're not arguing in good faith, but either have some kind of vendetta against me in particular (for reasons I can't even guess) or else just always argue to "win" rather than have an honest cooperative investigation of ideas.

they're assumptions it didn't even occur to us that we had taken any position about until something we didn't expect happens and we're pressed to explain what exactly about our expectations was in error. — Pfhorrest

But is this what we do? Is it even what we should do?

Penzias and Wilson switch on the machine, expecting not to be receiving a signal. But they are. That expectation has clearly not been met.

For you, what's been "falsified" is a a two- or three-layer cake: background assumptions, working theory, specific prediction. You think the next step taken is logical analysis, even if only implicitly: some member of the conjunction of the members of the set of beliefs held at the moment is false, making the conjunction false, preserving the truth of the conditional with a false consequent. Any falsehood will do for this to work, and in a sense this saves you from having to, per impossible, enumerate the background assumptions, because you can just examine them as they come up: if this one's still true, fish the next one out of the bag and check it.

While this is more or less fine from a logical point of view, it leaves out a lot of what we know about how people actually go about this, and how they can do so successfully, in a way that is worth the rest of us considering a model of rationality. You'll tend to shrug off some of this as if it's okay to have a general theory and a practical way of applying it -- but that's not okay in this particular domain, as ought to be obvious.

For instance, how are the background assumptions and theoretical commitments in your big conjunction ordered? Order doesn't matter for conjunctions. In what order are they examined? Is there a method, or is it more like the random 'fishing a belief out of a bag' I had above?

And what does it mean to examine a background assumption and see if it holds? Is that a logical process or is investigative, gathering more information? For instance, you could take an assumption, once somehow identified, and ask, could this be true and my original expectation fail? Swell, but the list of assumptions that will pass that test is uncomfortably large and most of them aren't helpful for what it sounds like they're trying to help with: not explaining the failure of the big conjunction, but the fact of the new observation, which happens to differ from what we expected but is a positive fact in its own right.

In real life, we don't churn through the big conjunction; instead we hypothesize explanations for the phenomenon it turns out we are observing, though we didn't expect to be. Penzias and Wilson look at the readout and are surprised. The question they will now try to answer is obviously, what caused this? Candidates include a fault or even a design flaw in the equipment, or maybe something obstructing the antenna. They're looking for a particular sort of thing that would cause a constant signal to be reported.

As you would have it, they consider statements like this: "If assumption A is false, that's consistent with prediction P failing." But in real life, people consider candidates like "If A2 is the case, that would cause P2" -- where A2 is one of the ways A could be false, and P2 is the observed way that P is false. There's an asymmetry here that cripples the formalist approach: "2 + 2 = ___" has one way to be true but a literally infinite number of ways of being false. That applies both to the prediction and to the so-called assumptions. We don't need a way of corralling those infinities because they're not real for people dealing with real problems.

You can try to layer on more formalism to bring your theorized process of belief revision closer to what we know people do and to what we know works -- rather in the style of talking about measuring the distance between possible worlds -- or you can just accept that the model you started with is actually getting in the way of understanding what really goes on and what is known to work.