What counts is that Bob's theory is distinct from George's theory.

And getting back on topic, what makes beliefs worthy of consideration at all is that they differ from one person to another, and with one person over time.

If the world were epistemically transparent, in such a way that we always agreed, and that we always knew what was true, there would be no need to seperate truth and falsehood, and no need to distinguish knowledge from belief.

SO, how do we tell that one person has a different belief to another...?

This is deeply anti-Cartesian.

Descartes failed to notice that in doubting all but his own doubt, he already admitted the language in which he could doubt; and hence he admitted the other that enables language.

Perhaps that 's @Hanover's error, too. The greater the primacy given to the self, the greater the need to contrast it with the other.

His theory could be expressable in principle, but still kept private. He probably just got tired of dealing with mean girls. — frank

Indeed, if it is not expressible, why call it a theory? If it is not expressible, then it is nothing.

But you could know how to do something and not be able to articulate that how. Stole that from Heidegger.

Sure. What cannot be said can be shown. I can't tell you how to ride a bike but I can show you.

Bike riding is not private.

IF i can't tell you what I believe, I can show you. Beliefs are not private, though they may be unexpressed.

What cannot be said can be shown. — Banno

I can't show you how to communicate (I'm talking about the more basic aspects of it, not superficial stuff like wording). You must already know how to do it in order for me to point to it.

It's just an example of something inexpressable. Does that make it private? I'm not sure what that would even mean. I don't know if that bears on what you're talking about. It's just more Heidegger.

Suppose that Bob's theory changes over the time spent on the island, but Bob doesn't notice. There's no written record to compare it to, and George has no idea.

Slowly, over time, Bob comes to think the exact opposite of what he first believed, but does not notice.

It would be very strange to claim here that Bob had a theory. — Banno

1. Why would it be strange to claim Bob had a theory?

2. If George understood Bob's theory, and both of their recollection changed over time, did Bob not have a theory?

1. Why would it be strange to claim Bob had a theory? — Hanover

So you are comfortable with Bob thinking that he has a theory that contradicts itself?

Bob believes A; over time, his belief changes to ~A, but he does not notice, and has no other way of understanding that his belief has changed, and hence he thinks he has the same belief.

You're OK with that?

Fine.

I can't show you how to communicate — frank

Really? So language is unlearnable?

innate

I'll leave that to science. That we learn the language of our family shows that language is learnable. A child of Russian descent who is adopted at birth by English speakers does not grow up speaking Russian.

How is this relevant?

I'm not saying it's fine or not. I'm just saying he apparently held two different beliefs at two different times and now he holds an incorrect belief that he's never changed his belief. I'm also saying George helps us none. There's no reason to believe George's recollection will be better than Bob's or that George won't just confuse matters due to poor recollection.

I'm just saying he apparently held two different beliefs at two different times and now he holds an incorrect belief that he's never changed his belief. — Hanover

We can see that he held two different beliefs.

That is, in order to understand this situation, we are needed.

Beliefs require the Other.

We can see that he held two different beliefs.

That is, in order to understand this situation, we are needed.

Beliefs require the Other. — Banno

This is just an empirically incorrect epistimological statement, declaring that the only way to establish knowledge of prior events is through witness testimony. Recording devices, physical evidence, personal recollections are all other ways, not withstanding that witnesses can just as easily forget as you can.

I'll leave that to science — Banno

You aren't persuaded by Chomsky?

I'm more interested in how we would manage to have the idea of privacy if, as you say, it's nothing.
How does that work in your view?

This is just an empirically incorrect epistimological statement, declaring that the only way to establish knowledge of prior events is through witness testimony. Recording devices, physical evidence, personal recollections are all other ways, not withstanding that witnesses can just as easily forget as you can. — Hanover

In the example - which you set up - recording devices, physical evidence, personal recollections are ruled out ex hypothesi. Any such device would make the example public, nullifying your argument.

I think the point is that it makes no sense to say that you could believe something which could not, even in principle, be either lingually expressed or shown by means of some perceptual behaviour; actions or pictures or whatnot.

I was just reacting to Banno's comment that if it's unexpressable, it's nothing.

Well if it cannot be expressed or shown then it may not be nothing, but it certainly cannot qualify as a belief. What could it be? Any ideas?

Various changes made to the exposition in the OP,

The interesting bit:

An individual's belief is inscrutable
I tried to defend the notion that to believe something is to act as if it is true. It didn't work, because one can act in ways contrary to one's beliefs. It's a result of the lack of symmetry between beliefs and actions mentioned above - Beliefs explain but do not determine actions. Thanks due to @Hanover.

Any belief can be made to account for any action, by adding suitable auxiliary beliefs.

You aren't persuaded by Chomsky? — frank

Interesting, but not demonstrated.

I'm more interested in how we would manage to have the idea of privacy if, as you say, it's nothing.
How does that work in your view? — frank

Yeah, serves me right for over-stating the case.

It's not nothing, it's irrelevant.

Edit: I see Janus said this before me.

Infelicities

• Error: believing one thing when another is true
• Lying: saying one thing is true while believing another
• Hypocrisy: Claiming a belief that is at odds with one's actions
• Akrasia: not being able to enact what one believes, for lack of will

I tried to defend the notion that to believe something is to act as if it is true. It didn't work — Banno

As you and recently @Janus have noted, in a propositional account of belief one argues not that belief must be expressed in fact, but that it must be expressible in principle.

Why not follow a similar line here? You could argue that beliefs are things that could be acted upon. Or as you put it, it must be possible to behave as if the belief were true. (And for free you get a way of distinguishing beliefs from each other.)

You could argue that beliefs are things that could be acted upon. — Srap Tasmaner

What of the ambiguity mentioned above - any belief could be used to justify any action, given suitable auxiliaries.

This appears to undermine any causal link between belief and act.

All of which is serving to reinforce my intuition that belief is hollow.

Ceteris paribus? It's "in principle" after all.

You could head for something like: given a set of beliefs, belief P is the belief which, if added to the set, eventuates in action A.

Or: belief P explains action A if P and only P is a member of every set of beliefs that explains A.

I can think of lots of models to test drive.

OK, let's take it for a drive...

Mad Mike builds rockets to launch himself into space so that he can see for himself if the Earth is flat or curved. Mike says he believes that the Earth is flat, and this explains his behaviour. But in the long night of the soul he admits that the Earth is round, and holds himself up as the champion of empirical method who will show it to be so.

belief P explains action A if P and only P is a member of every set of beliefs that explains A. — Srap Tasmaner

So what would belief P be in Mad Mike's case?

Further, what if there is no belief P that is a member of every set of beliefs that would explain A? After all, why should there be such a belief?

Hence, are Max's beliefs inscrutable?

In the example - which you set up - recording devices, physical evidence, personal recollections are ruled out ex hypothesi. Any such device would make the example public, nullifying your argument. — Banno

Two responses:

1. Why is a document written in my chicken scratch that is truly only decipherable by me "public," if It only conveys information to me and it helps me recollect prior events?, and

2. Why is having George available helpful in me recollecting past theories I've held if I have a better memory than him?

Thanks due to Hanover. — Banno

You're weh'cum

This is a thread about belief. — Banno

This reply is about a month late, but whatever. Yes, it is. Thank you for reminding me. But unless you or someone else says something that I disagree with, I will have very little to say. And, on the face of it at least, there's nothing in that quote which you've brought up that I disagree with.

So to explain why he launched himself in a self-built rocket, buggering his back, we say "Mad Mike Hughes believes the world is flat, and he wanted to prove it by flying in a rocket".

What this means is that Mad Mike acts as if the world is flat. What this does not mean is that there is a thing in Mad Mike's head that is a belief that the world is flat. — Banno

This reminds of those old realism vs. anti-realism debates, except here it's like you've swapped sides and have borrowed the anti-realist shtick of saying, "It's just a narrative".

I suppose it's possible that he doesn't really believe that the world is flat, and is merely acting as though he does, but if he does, as we have reason to believe, then his belief at least has an obvious relation to that thing in his head. After all, beliefs could not arise if it weren't for those things in our respective heads.