I'm pretty sure Bismarck is the capital of North Dakota — Srap Tasmaner

So it's use consists almost solely in your being able to answer a quiz question.

That does not show that knowhow and knowing are incommensurable.

So this:

...rather than the usual justificationist sense of rationalism, whereby no belief is justified until it can be supported from the ground up somehow, instead any belief is justified (including contrary ones) until there is support to the contrary, i.e. reason to rule that belief out -- an epistemological position called critical rationalism, supported by philosophers like Kant and Popper. — Pfhorrest

...was misleading in that you don't actually think knowledge is best defined in terms of critical rationalism.

So it's use consists almost solely in your being able to answer a quiz question.

That does not show that knowhow and knowing are incommensurable. — Banno

If my purpose is to answer such a question, but that's not why I learned it, so far as I know, and it might come in handy doing a Crossword too. What is the point of this?

I'm not sure why we're having this argument.

Is there some reason to avoid a commitment to people having either factual knowledge or (I looked it up now that I'm home from work) declarative memory, like Bismarck being the capital of North Dakota?

you don't actually think knowledge is best defined in terms of critical rationalism. — Banno

I do, but that is not in conflict with anything Quine has said, or that you or Isaac have said along the same lines as Quine.

It's getting harder and harder for me to care about the ontological part. (I also can't help but see the dual-process story as validating the reliance of Hume and Ramsey on "habit", though it feels a little tendentious.)

Philosophers tend to want to focus on the status of claims (is it a belief? is it knowledge?) and on the status an individual is imagined as assigning to their beliefs. But it might be possible to quit doing that. In the usual case of belief revision -- I thought there were two packs of poptarts but when I look there's only one -- does it matter that my belief was marked as revisable or defeasible? I do revise with minimal hesitation, if any. The "hunh" I grunt is, by introspection, mild curiosity about how there came to be only one or why I thought there were two, but there's very minimal tension associated with the belief revision itself. — Srap Tasmaner

I can see your point here. I was going to add to my explication of socially defined knowledge that individuals generally don't have a distinction between belief and knowledge for their own predictive thoughts. They're not treated differently, they don't appear differently neurologically, they're basically indistinguishable until they set them in a social context.

I wonder if there is really an issue there well described in terms of a belief's status at all, or if it's just more about reasoning processes, specifics of the evidence, etc. — Srap Tasmaner

Yeah, that would be my take too. Although, I think people are more similar on that front than in respect to belief formation than people who worry about 'critical thinking' tend to believe. This is the point I'm trying to drive home here. The target of the OP is non-existent. No-one thinks any other way than the way described. we do not form beliefs contrary to the evidence of our senses, and when beliefs need updating owing to new sensory information, we just do so (in a suitable conservative manner - we can't afford to be just changing our beliefs every few seconds)

The target of the OP, I think is the religious, the flat-earthers, the creationists, the anti-vaxxers, the climate change deniers etc. But most people form beliefs of that more complex sort on the basis of reports from members of trusted groups. I've not conducted any neuroanatomy, I believe all the things I believe about neuroanatomy because I think it's implausible that all the people involved and working with it are doing so deceptively, it has nothing at all to do with my senses (apart from my initial judgement of their trustworthiness). I am, for example, much more suspicious about the effectiveness of medicines, despite them also being investigated and tested by similarly qualified scientists, I basically can see much more of a plausible way in which their results might be skewed and so I've less inclination to trust them. At the end of the day, both are social judgements. The amount of scientific knowledge I personally have verified is tiny, the rest comes down to trust, the more people involved the potential deception, the less likely I deem it to be because I basically trust people not to be deceptive without due cause.

You must demonstrate that the first premise in the chain is incontrovertible. I do that in my theory here: https://thephilosophyforum.com/discussion/9015/a-methodology-of-knowledge
I do not want to distract from the OP's point here however. If you are interested in exploring how I solve this problem, feel free to visit. — Philosophim

I will perhaps have a read if I've time. I can't keep more than a couple of threads in mind at the moment. Perhaps in lieu of my doing so you could answer a few brief questions here?

How do you decide which is the first premise? Is it just the one you first thought of (temporally arranged)? In my example - A belief that A and a belief that evidence exists contrary to A (which we're calling a belief that B) - which is the 'first' premise and why?

Ah. Hence your inadequate response to Isaac. — Banno

What is so inadequate? He’s basically stating confirmation holism, as you pointed out, and I’m saying “no duh”. You rule out a complete network of beliefs, and replace it with something else that is not yet ruled out. Beliefs aren’t free-floating atoms, they’re all tied to other beliefs. — Pfhorrest

What you're not grasping (or ignoring, not sure which) is that it being "not yet ruled out" is itself another belief. The point of talking about Quinean Webs of Belief is not just to aggregate beliefs into little sub-net to be treated in exactly the falsificationist manner you propose. It's to undermine the idea that the belief in question and the cause to rule it out (or not) are different in kind. you cannot, therefore, make a distinction between those of the first kind on the basis of a lack (or presence) of those of the other.

it being "not yet ruled out" is itself another belief — Isaac

Except it's not, at least not on the same order as the beliefs under discussion. If anything, it's a meta-belief, an axiom of the method of belief revision. Being not ruled out is the default state of any belief under critical rationalism; it's not something that calls for justification. Critical rationalism turns the entire idea of justification on its head: rather than needing to have some belief to justify having some belief to justify having some belief, you may have whatever beliefs you like, until you encounter a reason why you can't.

That "reason why you can't" is not itself some other belief external to the rest of your preexisting beliefs, it's some inconsistency within your complete network of beliefs. That inconsistency, that ruling-out, does not compel any specific alternative belief, only that you revise something or other in your belief system to avoid that inconsistency.

And sure, when it comes to synthetic a posteriori beliefs, one usual element of that complete network of beliefs is that one's senses reflect something about the actual world, which is equivalently to say, a rejection of the notion that there is some "actual world" aside from the world accessible to the senses. One could always reconcile any observation with any beliefs if one just disbelieved that observation conveyed any truth. But I think there are, and have stated extensively elsewhere, reasons to reject that kind of disbelief in observation; which is to say, inconsistencies that would inevitably arise from accepting that kind of rejection of observation.

And yes, the methodology of critical rationalism itself, which is equivalently to say the rejection of justificationism, could also be considered a belief on the same order as that reliance on observation, a kind of meta-belief if you will. But there are, again, reasons to reject justificationism, which is to say, inconsistencies that arise from the acceptance of justification, which I have also already detailed elsewhere. And since even justificationism itself accepts proof by contradiction as justification within its paradigm, that should be sufficient to disprove justificationism itself from within justificationism, and so compel critical rationalism.


But this thread in particular is not supposed to be an argument for critical rationalism in general. It's just supposed to show that the Gettier problem does not apply within a critical rationalist paradigm, because it hinges on justificationist assumptions. If you already reject those assumptions, because you already reject justificationism, because you're a critical rationalist, then the Gettier problem means nothing. And existing responses to Gettier, like Nozick's, already hint at that, without (so far as I know) coming out and saying it outright.

That "reason why you can't" is not itself some other belief external to the rest of your preexisting beliefs, it's some inconsistency within your complete network of beliefs. That inconsistency, that ruling-out, does not compel any specific alternative belief, only that you revise something or other in your belief system to avoid that inconsistency. — Pfhorrest

That it is inconsistent is a belief. You can't escape this, it still forms the same structure - my belief that A, and my belief that B, and my belief that A is inconsistent with B - all beliefs, all of equal status, none prior, or beneath, or more fundamental or any of these distinguishing features you'd like to attach. They're not there.

The problem here is not critical rationalism, or justificationism, or fideism as methods of distinguishing knowledge from belief - it is the assumption that there exist methods of distiguishing knowledge from belief at all at the ontological level you want them to exist.

methods of distinguishing knowledge from belief - it is the assumption that there exist methods of distiguishing knowledge from belief at all at the ontological level you want them to exist — Isaac

That you think I'm trying to distinguish knowledge from belief or that this has anything to do with ontology shows a complete misunderstanding of what I'm talking about at all. On my account, knowledge is a kind of belief, not something separate from it, and what we're discussing in epistemology generally is how to (practically) revise beliefs, in a way that avoids various problems that might otherwise arise in that activity. Epistemology is about identifying what problems might arise in that activity of belief-revision, and seeking out ways around them. Knowledge is just the subset of belief that can make it through such a process.

On my account, knowledge is a kind of belief, not something separate from it, and what we're discussing in epistemology generally is how to (practically) revise beliefs, in a way that avoids various problems that might otherwise arise in that activity. Epistemology is about identifying what problems might arise in that activity of belief-revision, and seeking out ways around them. Knowledge is just the subset of belief that can make it through such a process. — Pfhorrest

None of that is surprising to me and yet I still don't feel you've answered my charge, so the problem can't be in that distinction alone.

You say "Knowledge is just the subset of belief that can make it through such a process." I'm fine with that, so let's say we agree there. The issue is then the nature of the process, with which there can be two issues

1) whether it does indeed define any subset at all - ie if all beliefs pas this process then it doesn't define a subset, it just defines the set.

2) whether, assuming it does define a subset, that subset is correctly called 'knowledge' given that 'knowledge' is already a term in common use.

I disagree with your proposed method on both counts. On the former because no beliefs are ruled out by your method, it therefore defines all beliefs, not a subset of them, and the latter because we simply don't use 'knowledge' that way, as the term cannot refer to private justification and still retain a public meaning.

Were I doing a PhD, — Banno

...then definitely use divers with one e.

Yep. @Pfhorrest seems to have missed the force of Quine's critique.

Critical rationalism turns the entire idea of justification on its head: rather than needing to have some belief to justify having some belief to justify having some belief, you may have whatever beliefs you like, until you encountera reason why you can't. — Pfhorrest

A "reason why you can't" will still be underdetermined...

A "reason why you can't" will still be underdetermined... — Banno

I addressed underdetermination specifically in the very post you quoted:

That inconsistency, that ruling-out, does not compel any specific alternative belief, only that you revise something or other in your belief system to avoid that inconsistency — Pfhorrest

Critical rationalism does not find undertermination a problem; you're never trying to justify one specific possibility, only narrowing the range of possibilities, so there are always a range of possibilities remaining.

...only narrowing the range of possibilities... — Pfhorrest

How? So far as I can see, you have not shown how.

Can you perhaps give an example? "...and you can show that B and C are contrary to each other"; the point of underdetermination is that you can't show this. There are innumerable reasons why A and B might appear to be contradictory, and yet not.

How do you decide which is the first premise? Is it just the one you first thought of (temporally arranged)? In my example - A belief that A and a belief that evidence exists contrary to A (which we're calling a belief that B) - which is the 'first' premise and why? — Isaac

1. Have a belief A
2. Demonstrate that it is impossible for A to be contradicted through deduction.
3. A can become a prime premise for B, etc.

Again, I spend a few paragraphs on it, with lead up there. If you want to know how I do that, or if you think the above does not satisfy what you are looking for, it is best we take the conversation there, and not distract from the thread here.

The target of the OP, I think is the religious, the flat-earthers, the creationists, the anti-vaxxers, the climate change deniers etc. But most people form beliefs of that more complex sort on the basis of reports from members of trusted groups. — Isaac

That's the low-hanging fruit, but I think the real motivator, in terms of cultural history, is Nietzsche, Freud, Marx, and Darwin. It's Freud in particular: the revelation that we have something like "unconscious thoughts" and, more importantly, unconscious motivations, and unconscious commitments is troubling to people careful about how they think. In the modern context, it's the widespread awareness of unconscious bias. Nietzsche (and then Heidegger, Derrida, Sartre) has all sorts of things to say about failings of the intellectual conscience, of bad faith, of having some inauthentic weltanschauung, of all sorts of self-deception. Marx offers an explanation of the source of some of those, Darwin too (Hoffman with his "desktop" thing). Whether you buy the grand narratives, nowadays you can't get around knowing that your reasoning might be motivated in a way We Don't Approve Of: on top of the "fallacies" so beloved on this forum, which are easily sussed out, there is the fact of racial bias, recency bias, availability bias, and all the rest. You might even think you're flailing away in the prison of a Kuhnian paradigm, desperately fighting off an alternative to your position just because it's not your position. You might just be a captive of your Whorfian language, thinking the thoughts you happen to have words for and no others. I haven't even mentioned feminism, which says something about me!

The variations on this worry go on and on. We are obsessed with the possibility of self-deception.


Bonus reference

Should have mentioned Wittgenstein too (and Sellars). How do I know my argument is what I think it is? Am I actually relying on a simplistic picture I have of how this works? Am I taking words that make sense in one context and smuggling them into another context as if they still have that meaning?

1. Have a belief A
2. Demonstrate that it is impossible for A to be contradicted through deduction.
3. A can become a prime premise for B, etc. — Philosophim

This still doesn't address Quine.

1. Have a belief A
1a. Also have a belief C
2. Demonstrate that it is impossible for A to be contradicted through deduction.
2a. Also demonstrate that it is impossible for C to be contradicted through deduction.
3. A can become a prime premise for B, yet C can become a premise for ~B.

It's that which Quine shows. Our theories (beliefs that B) in your example, are underdetermined. A large number of otherwise consitent beliefs can be marshalled to support or diminish B. We have no mechanism for choosing which.

I've read the first and second of your essays, but neither address the degree to which deductive beliefs form networks. You take a single example and extrapolate merely assuming that the added complexity of vast numbers will have no effect. Even if it were theoretically possible to thus ground beliefs (I maintain it isn't, but this is a lower hanging fruit), it would be pragmatically impossible due only to the absolutely vast number of beliefs involved, each of which would have to be independently disentangled from the other. With only 10 beliefs you have 3,628,800 arrangements to go through.

I've read the first and second of your essays, but neither address the degree to which deductive beliefs form networks. — Isaac

Oh fantastic! Lets take it there then. The first two build up knowledge from the self-subjective viewpoint. Part 3 goes into how knowledge works within society. I would love your comments on it there. Part 3 should answer how we resolve the point from Quine.

I think the real motivator, in terms of cultural history, is Nietzsche, Freud, Marx, and Darwin. It's Freud in particular: the revelation that we have something like "unconscious thoughts" and, more importantly, unconscious motivations, and unconscious commitments is troubling to people careful about how they think. — Srap Tasmaner

That's an interesting way to look at it. There's certainly a common thread, a discomfort, with psychology and neuroscience, that we're intruding where we're not welcome (faced some pretty nasty backlash even within these sanctified walls), I think this sense might be behind some of that. There's a certain tranche of philosophers for whom the potential inability of the brain to act as a measure of the truth of its own conclusions would undermine their whole project.

Should have mentioned Wittgenstein too (and Sellars). How do I know my argument is what I think it is? Am I actually relying on a simplistic picture I have of how this works? Am I taking words that make sense in one context and smuggling them into another context as if they still have that meaning? — Srap Tasmaner

This too, especially the last (I think I should read Sellars). We had a massive thread a while back on "What it's like", as if the fact that I can ask what that lemon cake was like makes asking what being a human is like make any sense.

One of the things that interests me about how people write here is that philosophical methods of defending beliefs differ from those employed in more general senses. Less social perhaps, more precious about the integrity of the 'method' than content. Hinting that such a method may be nothing but post hoc rationalisation and underdetermining anyway seems like a fraught undertaking.

philosophical methods of defending beliefs differ from those employed in more general senses — Isaac

It would be interesting, as a matter of history, to see how this plays out in Plato, where the standards of justification are in play as various justifications are examined. It's a very old thing for philosophy, to find common sense wanting -- too casual, too unsystematic, too inconsistent. Even in Plato you see accusations of bias (of course you think X because you're A). I've sketched some of the ways I think this downright fear of ordinary thinking has been ratcheted up, because now we know it can be invisible! (And even when it's visible, and right in front of you, you might not recognize just what you're relying on. That's the net result of "ordinary language philosophy".)

At any rate, the message has gotten through that to do philosophy right you have to rely on special methods of justification, and probably specialized vocabulary invented just for the purpose, and so on. That this can look, if you squint, a bit like how science deviates from common sense is all the more encouraging.

Coming back to the matter at hand, philosophical problems like the subject of this thread just look different if you start from a modern science-aware world-view. Here's how Dewey begins Democracy and Education:

The most notable distinction between living and inanimate things is that the former maintain themselves by renewal. A stone when struck resists. If its resistance is greater than the force of the blow struck, it remains outwardly unchanged. Otherwise, it is shattered into smaller bits. Never does the stone attempt to react in such a way that it may maintain itself against the blow, much less so as to render the blow a contributing factor to its own continued action. While the living thing may easily be crushed by superior force, it none the less tries to turn the energies which act upon it into means of its own further existence. If it cannot do so, it does not just split into smaller pieces (at least in the higher forms of life), but loses its identity as a living thing.

As long as it endures, it struggles to use surrounding energies in its own behalf. It uses light, air, moisture, and the material of soil. To say that it uses them is to say that it turns them into means of its own conservation. As long as it is growing, the energy it expends in thus turning the environment to account is more than compensated for by the return it gets: it grows. Understanding the word "control" in this sense, it may be said that a living being is one that subjugates and controls for its own continued activity the energies that would otherwise use it up. Life is a self-renewing process through action upon the environment.

That was 1916. There's really nothing much here that couldn't have been written long before, no mention of evolution at all, but it's a starting point suffused with the impact of Darwin. This passage doesn't even nod at human beings per se, but you know this is exactly what he has in mind: a human being is an organism living in an environment, start from there. Dewey really thought Darwin would completely reshape the entire landscape of philosophy, but a hundred years later it feels like that change has barely begun. We're still writing footnotes to Plato.

The traditional philosophical definition of knowledge, dating back at least to Plato, is that knowledge is justified true belief. That is to say that it is not enough merely to believe something to be the case, and it is not even enough for that belief to turn out to be true, but for someone to know something they must also have a justification for their belief, a reason to believe it, because it would not constitute knowledge to simply guess at an answer to a question (or otherwise come to believe it for insufficient reason) and just by luck turn out to be right. — Pfhorrest

I have a rather low opinion of thinking book learning equals having knowledge. I will go with Thomas Nagel and the notion that there is an explanatory gap between understanding the physical world and understanding conscious experience. I will go further and say without experience one does not have an adequate knowledge of the physical world. Young people accumulate facts but it is not until our later years that those facts begin to have a sense of meaning. That is the big problem with getting people to cooperate with wearing masks and distancing. Until they experience the reality of Covid by becoming ill or losing a loved one, the talk of wearing mask and distancing and warnings to not have gatherings, the number of people who died, etc. is just meaningless words. Words they don't want to hear. Blah, blah, blah. But when the truth comes home those words have meaning and the behavior is changed.

Edmund Gettier has since proposed that even justified true belief is not enough to constitute knowledge, to the extent that reasons to believe something can sometimes be imperfect, can suggest beliefs that nevertheless turn out to be false, yet we nevertheless want to say that someone can still be justified in believing something for such reasons. Because if justification can be imperfect, someone could be justified in believing something that, despite that justification, might nevertheless turn out to actually be false, and in such cases we would not want to say that it counts as knowledge to be misled by imperfect justifications to believe something that could nevertheless have still been false but, by an unrelated coincidence, does happen to also be true, just not for the reasons justifying the belief.

For all the rest, I will be pragmatic. We should never believe we know absolute truth for the reasons you explained. On the other hand, we need a starting point so I am in favor of treating our agreed truths as knowledge. It is our knowledge until better reasoning changes it.

I will even go out on a limb. I will say what we think we know, is knowledge, even if no one agrees with us. An example is knowing bacteria leads to infections and disease, and therefore, sanitation is essential. That is a fact of life even if no one agrees. It took the scientist a hundred years to convenice doctors sanitation is essential. And when we have knowledge that others do not have, it is our duty to continue the effort of pursauding others to accept that truth. That is essential to democracy. Education for "group think" has been detrimental to our democracy. Independent thinking may mean standing alone with a truth for a long time before winning the argument. We may even die before the truth is accepted.

Being not ruled out is the default state of any belief under critical rationalism; it's not something that calls for justification. Critical rationalism turns the entire idea of justification on its head: rather than needing to have some belief to justify having some belief to justify having some belief, you may have whatever beliefs you like, until you encounter a reason why you can't. — Pfhorrest

This seems to be suggesting that all beliefs, until and unless they are ruled out, enjoy equal status. What happened to the reasons we hold beliefs in the first place? Are you not leaving perceived degrees of plausibility (themselves perhaps determined by social, cultural and psychological influences) out of the picture? What about beliefs that cannot be definitively ruled out; for example beliefs in compassion, love, sacred beauty, or ethical virtues?

Or do you see yourself as dealing just with empirically testable beliefs? Even there how would you know that "a reason why you can't" is definitive or compelling?

Can you perhaps give an example? "...and you can show that B and C are contrary to each other"; the point of underdetermination is that you can't show this. There are innumerable reasons why A and B might appear to be contradictory, and yet not. — Banno

Can you give an example to the contrary?

I'm talking about scenarios where you have a belief system like "A" plus "A implies B", and then a new belief that "not-B". That is straightforwardly just a logical contradiction, and you have to change something about it on pain of inconsistency. At this point we're not even talking about observational evidence, just pure abstract logic. Whatever your reasons for believing that A, that A implies B, and that not-B, something somewhere in some of those reasons must be wrong, because you just can't have all of those at once.

What's underdetermined is what exactly went wrong where:

You could reject not-B, on the grounds that A and that A implies B, and then make all of the subsequent changes to the rest of your beliefs that are required to not demand you accept not-B.

Or you could reject that A implies B, on the grounds that A and not-B, and then make all the subsequent changes to the rest of your beliefs that are required to not demand you accept that A implies B.

Or you could reject A on the grounds that A implies B and that not-B, and then make all the subsequent changes to the rest of your beliefs that are required to not demand that you accept A.

As I understand Quine, his point was that things aren't as simple as just one of those scenarios. It's not like you just observe that not-B and boom, there you go, we know for sure that not-A. The implication from A to B is also up for revision, as is the observational implication that not-B in the first place. You can change any of those to salvage the consistency of your belief system.

And I have no problem with that, that's a big "no duh" to me.

This seems to be suggesting that all beliefs, until and unless they are ruled out, enjoy equal status. — Janus

Yes. Nobody's beliefs have a particular burden of proof over anyone else's. If you want to push your beliefs over someone else's, you've got to show that theirs are wrong, and more so that all the other alternatives besides yours are wrong; and saying "you can't prove they're right" is not showing they're wrong.

What happened to the reasons we hold beliefs in the first place? Are you not leaving degrees of plausibility (themselves determined by social, cultural and psychological influences, out of the picture? — Janus

Everyone thinks they have good enough reasons to hold their beliefs. Those degrees of plausibility can factor in to your own evaluation of what seems most likely to you, but if someone else disagrees with the plausibility of a certain belief, if it just doesn't seem the same to them as it seems to you, then you have to agree to disagree until one of you can definitively show that the other is actually wrong.

What about beliefs that cannot be definitively ruled out; for example beliefs in compassion, love, sacred beauty, or ethical virtues. — Janus

I'm not sure what you even mean by "belief in" compassion, love, or sacred beauty. That sounds like a different sense of the word "belief" that means "support". I don't think there's any practical controversy over the fact that people sometimes are compassionate, or loving, etc. But if there were any question about those things, it would be an empirical question.

Ethics is a good question though. I do think that ethical views can be definitively ruled out, but that the method for doing so is not quite "empirical" in the usual sense, though it is analogous. This is a huge can of worms I don't want to open with Isaac in the room though. In any case, critical rationalism in general is not specifically about empirical beliefs; the specific subset of critical rationalism about empirical beliefs is falsificationism. The critical rationalist methodology can be used on any kind of belief though, not just empirical ones.

Yes. Nobody's beliefs have a particular burden of proof over anyone else's. If you want to push your beliefs over someone else's, you've got to show that theirs are wrong, and more so that all the other alternatives besides yours are wrong; and saying "you can't prove they're right" is not showing they're wrong. — Pfhorrest

When I mentioned perceived degrees of plausibility and that they may be more or less determined by social and cultural influences, you responded with "everybody thinks they have good reasons for holding their beliefs", which seems to ignore the possible incommensurability of different people's basic assessments of what constitutes plausible reasons. So, a great glaring example of this kind of thing is the never ending theism/atheism debate. Of course, there are many much more subtle cases, too. How can you ever falsify either position, unless the starting assumptions about what constitutes a plausible reason for belief are shared?

I'm not sure what you even mean by "belief in" compassion, love, or sacred beauty. That sounds like a different sense of the word "belief" that means "support". I don't think there's any practical controversy over the fact that people sometimes are compassionate, or loving, etc. But if there were any question about those things, it would be an empirical question. — Pfhorrest

I meant believing in the importance of those things for human life. Some do and some don't, or different people accord different degrees of importance to those and other qualities. I don't think such beliefs can be assessed strictly empirically, but if they were taken to be to be subject to empirical investigation, then that belief itself would be the result of adopting certain starting assumptions.

How can you ever falsify either position, unless the starting assumptions about what constitutes a plausible reason for belief are shared? — Janus

You have to work your way down through the networks of supporting beliefs until you find something in common to work back up from. This may take you a long way from where you started into far more abstract territory, and odds are they won’t want to go on that long journey with you, but that’s how you’d have to do it.

For example my whole belief network is grounded in my philosophical principles which are grounded in pragmatic reasons that anyone worth talking to would share: basically, “You care about something right? There’s something or another you’re trying to do in your life that you would rather succeed at than fail at, no? Well, here’s why being able to discern truth from falsehood is important for succeeding at all other things, and here’s why these principles are important for succeeding at the task of discerning truth from falsehood, and here’s some broad implications of those principles, and here are some specific big beliefs that run counter to those implications, so if you care about anything then if you’re really consistent you’ll reject those particular beliefs and then make whatever adjustments necessary to the rest of your beliefs to accommodate that.”

“You care about something right? There’s something or another you’re trying to do in your life that you would rather succeed at than fail at, no? Well, here’s why being able to discern truth from falsehood is important for succeeding at all other things, and here’s why these principles are important for succeeding at the task of discerning truth from falsehood, and here’s some — Pfhorrest

Yes, but what happens if you apply this, for example, to theism? There are many scientists who are also theists, and this apparently doesn't hamper their ability to do science just as well as an atheist scientist. Also there are studies that purport to show that theists live longer, are healthier, and so on than atheists. Assuming for the sake of the argument that these claims are correct, then how would you go about disabusing the theist of his or her "false" beliefs (assuming that you believe they are false, of course).

You have to work your way down through the networks of supporting beliefs until you find something in common to work back up from. — Pfhorrest

What if you can't find any? Say, for example, that someone believes that scripture is the ultimate evidence that outweighs all other sources? How are you going to find something in common to work back up from with such a person?

Yes, but what happens if you apply this, for example, to theism? — Janus

I was thinking of theism as I wrote that, as one of those "specific big beliefs".

There are many scientists who are also theists, and this apparently doesn't hamper their ability to do science just as well as an atheist scientist. — Janus

I think they're compartmentalizing their work from the rest of their thought, and so being inconsistent.

If they don't care that they're inconsistent, then there's nothing to do about it.

Also there are studies that purport to show that theists live longer, are healthier, and so on than atheists. — Janus

That has no bearing on the truth or falsity of (a)theism, and in principle it should be possible to suss out exactly what it is about a certain kind of belief (or what correlates with that kind of belief) regardless of its truth or falsity that's contributes to health and long life, and replicate those effects for atheists too. (My first hypothesis would be that theism is a common but not necessary consequence of excessive optimism, broadly speaking, in one's thought patterns, and that optimism generally has health benefits).

What if you can't find any? Say, for example, that someone believes that scripture is the ultimate evidence that outweighs all other sources? How are you going to find something in common to work back up from with such a person? — Janus

If they really believe scripture above absolutely everything else, and there is nothing that they care about more than conforming their beliefs to scripture, then they're a lost cause. Like the scientist above who doesn't care if they're inconsistent, if they really just don't care, then I don't care to struggle pointlessly trying to convince them otherwise.

But I think that's probably pretty unlikely, for most people. They probably have reasons for believing scripture, that stem from deeper concerns, which may stem from deeper concerns, and so on. Probably most people care more about their life and well-being than they do with just agreeing with some book just because, and the reason why they agree so vehemently with the book could easily be that they think it will contribute to their eternal life and well-being. That's an avenue to start looking for some common ground, because I also care about their life and well-being, even though I don't believe in their scriptures, and if they had to choose between abandoning the scripture of abandoning their life and well-being (and were convinced that that actually was a choice between two different things, not tantamount to the same thing), I'd suspect (and hope) that they'd pick their life and well-being over the scriptures.

I think they're compartmentalizing their work from the rest of their thought, and so being inconsistent.

If they don't care that they're inconsistent, then there's nothing to do about it. — Pfhorrest

But they're not necessarily being inconsistent on their own terms, even if they are on yours.

(My first hypothesis would be that theism is a common but not necessary consequence of excessive optimism, broadly speaking, in one's thought patterns, and that optimism generally has health benefits). — Pfhorrest

I think it is more likely that theism is the source, not the result, of excessive optimism. To gain that optimism, in the face of the pessimism that might attend the realization of inevitable suffering, loss, injustice and annihilation, some people are drawn to the idea of a transcendent reality. I believe the same impulse is there in the case of Hinduism and Buddhism and most other religions too.

If they really believe scripture above absolutely everything else, and there is nothing that they care about more than conforming their beliefs to scripture, then they're a lost cause. Like the scientist above who doesn't care if they're inconsistent, if they really just don't care, then I don't care to struggle pointlessly trying to convince them otherwise — Pfhorrest

Yes, but you're assuming that what you count as evidence is more compelling than what they count as evidence. In the general context of modern philosophy of course you are assumed to be right and they wrong. I don't think faith is inconsistent with modern philosophy, though. There are modern philosophers I admire who are also theists. I don't see them as being inconsistent, but as adopting different starting assumptions than I do; having different reasons for their beliefs. Wherever faith is in play I think it ought to be acknowledged as such, of course; but that goes for both sides of the argument.

That's an avenue to start looking for some common ground, because I also care about their life and well-being, even though I don't believe in their scriptures, and if they had to choose between abandoning the scripture of abandoning their life and well-being (and were convinced that that actually was a choice between two different things, not tantamount to the same thing), I'd suspect (and hope) that they'd pick their life and well-being over the scriptures. — Pfhorrest

The people you are talking about probably care about their eternal life and well-being. You don't care about that because you don't believe in it. That belief need not impact whatsoever on their material life and well-being; how would you ever, why would you ever try to, convince them that it could, when your belief that it could is, according to all the evidence, false?