Monday, March 05, 2018

The Signature of God

I think belief in God reasonable only if it is based on considerations available to all humans: not if it is claimed on the basis of a special message to oneself or to the group that one belongs.
Anthony Kenny ("Knowledge, Belief, and Faith," Philosophy 82, 381-97)
      So what better signature of the creator of homo sapiens than an elementary logical proof that there is a God? In my last post, I described the argument that given some things, cardinally more selections from them are possible.
      That post ended with a brief description of how that means that paradox arises: we naturally assume that each of the possible selections that such endlessly reiterated selection-collections and infinite unions would or could ever show there to be is already a possibility, that it is already there, as a possible selection; it would follow that they were all there already, that they are collectively some impossible collection of all those possible selections.
      Logic dictates that we have made some mistake; and this version of Cantor's paradox arises because we are considering combinatorially possible selections: that is why the sub-collections that define those selections were able to become so paradoxically numerous, why the paradoxical contradiction did not just show that there are not, after all, so many extra things, over and above the original things.
      My resolution begins by observing that apparently timeless possibilities could, possibly, become more numerous over time; it begins that way because if possible selections are always becoming more numerous, then we would never have all of them. A Constructive Creator could, possibly, make the definitive selections; and if that is the only logical possibility, then that is what has been shown.
      Note that serious mathematicians have taken Constructive mathematics seriously, and when constructed by a transcendent Creator the mathematics would be much more Platonic, and much more Millian. Consider, for an analogy, how God's commands could, just possibly, define ethics. And note that such creative possibilities are not that different to the Creating of mere things ex nihilo, if you think about it: how is such Creation even possible? For us, the laws of physics present immutable limits to what can be done; for a God, such laws are, metaphorically, a brushstroke.
      We live in a world of things, and numbers of things; and for us, numbers appear timeless. But logic does seem to say that such numbers are impossible. When we first think of the origin of things, we might think of things that could have been there forever, like numbers. But logic seems to say that there was originally stuff, not things; perhaps mental stuff, perhaps a God that is not exactly one thing. There would have been some possibility of things, and more arithmetic the more that God thought about that possibility.
      I should add a note about what sort of God is being shown to exist. The proof does not show that God could not have created a four-dimensional world in a Creative act above and beyond that temporal dimension. So this God might be what we call "timeless," and might know all about the future; or not. And either way, this God could always have known all of our textbook mathematics, if only because that is essentially axiomatic.

Saturday, March 03, 2018

Cantorian Diagonal Argument

Cantor’s diagonal argument that there are more real numbers than natural numbers gets its name from its picture proof (as below), and it generalizes to show that powersets are always bigger than their original sets.

Cantor originally used collections instead of sets, but they gave him a paradox. Now, a collection of things is just those things being referred to collectively, so it is hard to see how that could have been the problem. But Cantor introduced the notion of a set, or consistent collection, and most modern mathematicians use axiomatic sets, for added confidence, and define numbers from them.
      Nevertheless, there really are numbers of things, so I take the logical essentials of Cantors paradox, and find a lacuna. My version of the diagonal argument shows that given some things, cardinally more selections from them are possible. As is the case with Cantor’s diagonal argument, it is best to begin with small collections, and build up from there, so that the general case can be more easily understood, by comparison with those simpler cases.

There are clearly three things:
      clearly there are
Given those three words, we can select a couple, e.g. ‘clearly’ and ‘there.’ There are three ways of making a pair – three different pairs that could be made – from those three words: {‘clearly,’ ‘there’}, {‘there,’ ‘are’} and {‘clearly,’ ‘are’}.
      Each of those ways of making a pair derives from, and is therefore defined by, the presence of two particular things in the original collection. Given those two things, there is that way of making a pair, whether or not anyone would or could make it. Because the original things were distinct, those pairs are distinct, and so each can count as one thing, as when we think of those three ways of making a pair. Possible selections are, in that sense, things.
      In a similar sense, collections are things, e.g. those are three collections of words. But given some things, thinking of just some of them as yet another thing can easily seem like the weak link in a chain of reasoning that leads to a contradiction. (After all, the collection of one thing is just that thing.) It is clearer that, given some things, a way of making a pair from them is indeed another thing. (A way of selecting just one thing is a way of selecting.)

Making a pair is just one way of making a selection. There are, in total, 2 to the power of 3, or 2^3= 8 possible selections from a collection of 3 things (cf. its powerset). It is an elementary result in combinatorics that there are 2^3 ways of assigning 2 labels, say ‘In’ and ‘Out,’ to 3 things, e.g.
      for the pair that is ‘clearly’ and ‘there,’
      ‘clearly’ has the label ‘In,’ as does ‘there,’
      while ‘are’ has ‘Out’ because it is not in that sub-collection.
In general, for any collection of things, T, there is a selection-collection, S(T), of all the combinatorially possible selections from T, each corresponding to some combination of as many ‘In’s and ‘Out’s as there are things in T.
      There is the selection-collection of 2^8 = 256 possible selections from the aforementioned 8, for example; and there are, similarly, a further 2^256 possible selections from that collection, and so on.
      Each of those possibilities is distinguished and defined by the presence of pre-existing things in the original collection, and so they are all implicitly there already, with our original 3 things.
      There is therefore an infinitely big collection of combinatorial possibilities, say N (from which further selections might possibly be taken, giving us S(N); and so on).

Two collections of things have the same cardinal number of things when there are one-to-one mappings from each collection onto all of the other. Cardinality therefore captures some of the intuitive sense of there being as many things in one collection as there are in another. Whether cardinal numbers are rightly called ‘numbers’ or not does not matter here; for the purposes of this proof, the main thing about cardinality is that it is an equivalence relation: it is reflexive, symmetric and transitive. Cardinality therefore partitions collections into equivalence classes. In particular, S(N) is not in the same class as N, for the following reason.

For simplicity, the things in N will be given the names
‘1’ (e.g. naming {‘clearly,’ ‘there,’ ‘are’}),
‘2’ (e.g. naming {‘clearly,’ ‘there’}),
‘3’ and so forth. To get the things in S(N) we associate the things in N with either ‘In’ or else ‘Out,’ and so each thing in S(N) can be named by an infinite sequence of ‘I’s and ‘O’s.
      If S(N) had the same cardinality as N, then we could associate each combinatorially possible sequence of ‘I’s and ‘O’s with one of the names of the things in N, and thereby list all the combinatorially possible sequences of ‘I’s and ‘O’s.
      E.g. the element of S(N) whose name is the sequence I, I, O, O, … might be associated with the element of N named by ‘1,’ and so on:

 N         S(N)

 1           I           I         O         O         …

 2          O         O         I          O         …

 3           I          O        O         O         …

 4           I          O         I           I         ...

…         …         …        …         …         ...

If we can name an element of S(N) that is not in that list (for any such list), then that will show that N and S(N) are not the same size; and we can specify one that is different from each of those by specifying that:
its 1st label differs from the 1st label of the element associated with 1,
its 2nd label differs from the 2nd label of the element associated with 2,
and so on (e.g. O, I, I, O, ...). And that diagonal argument generalizes to show that every selection-collection, S(T), is cardinally bigger than its original collection, T, as follows.

We begin by supposing, counterfactually, that S(T) has the same cardinality as T, i.e. that there are one-to-one mappings from T onto all of S(T). Let M be one such mapping.
      We use M to specify a collection D as follows: for each thing in T, if the possible selection that M maps that thing to includes that thing (in other words, if that thing has the label ‘In’ in that possible selection) then D does not include it (it has the label ‘Out’ in D), but otherwise D does; and there is nothing else in D.
      Since the only things in D are things in T, D should be in S(T); but according to its specification, D would differ from every possible selection that M maps the things in T to. Consequently there is no such M; S(T) does not have the same cardinality as T. And since S(T) has at least one element for each thing in T – e.g. the selection of that thing – hence S(T) is bigger than T.

So, given any 3 things, there is an infinitely big collection, N, and an even bigger collection, S(N), and the even bigger S(S(N)) = S^2(N), and similarly S^3(N) and so on.
      All the things in all those collections are collectively the union, U, of those collections; so, there is also U. U is bigger than each of those S^n(N), for natural numbers n, because it contains all the things in each S(S^n(N)). Furthermore S(U) is even bigger, and so on. So there is also the union, say V, of all the S^n(U) for natural numbers n. S(V) is even bigger, and so on; and so forth, past W, say.
      There will be a union, UU, of U, V, W, …, and thence a union, UV, of all the S^n(UU), and similarly UW, and so on, through VU, VV, VW, ..., and so forth. There will be a union, UUU, of UU, VV, WW, …, and a union of U, UU, UUU, …, and so on, and so forth.

Paradox arises because we naturally assume that each of the possible selections that such endlessly reiterated selection-collections and infinite unions would or could ever show there to be is already a possibility, that it is already there, as a possible selection. It follows that they were all there already, that they are collectively some collection, C, of all those possible selections.
      But, there cannot be any such collection, because its elements, simply by existing, would define those of S(C); and by the diagonal argument, S(C) would contain even more things of that very kind. And we cannot – by the meaning of ‘not’ – have both that C does contain all such possible selections and that C does not contain them all.

      [Lacuna]

Friday, March 02, 2018

an inconvenient Proof ?

Do I have a proof that there is a transcendent Creator?

Well, the essence of Cantor's paradox is a logical argument for a contradiction, with an obscure lacuna: there need be no contradiction if arithmetic (that is Millian, or ordinary, common or garden arithmetic) is constructed forever. Were it not for that lacuna, we might have to throw logic away and replace it with some formal logic (symbolic calculi called "logics") or other, whilst being unable to choose logically between them. But, there is that lacuna, and so we do have a proof of the existence of a transcendent constructor of arithmetic; and of course, Millian arithmetic could only be constructed by the Creator of all other things.
      Note that a purely logical existence proof would be the appropriate signature of the Creator of homo sapiens. And consider some other kinds of proof, by way of comparison; here are a couple of examples:

Suppose there was a serious crime. Fortunately you have a suspect, and a good case against him. The defense says that your case means nothing, because you are only human, that to err is human. She goes on to detail how nice your suspect is. You point out that she should therefore doubt that opinion of him, since she is human, whilst you need not entertain any such doubts because it is not your argument; indeed, you have convicted lots of criminals on less evidence, so you ask her if they should all go free? Of course not, she says, it is only your case against this man that is thrown into doubt by our common humanity, because he is so very nice indeed! She has simply ignored your observation about her own humanity; maybe she erred in doing so! But what should we conclude from an assumption that we cannot trust our conclusions?!
      Let us suppose that your case is exceptionally water-tight: there is lots of physical evidence, and everyone else has cast-iron alibis, while your suspect has no alibi at all; and this crime is just the sort of thing that he would do. There really is no reasonable way that your suspect is innocent. He even bragged about his guilt to you in private. Since your case is so water-tight, hence all her talk about your humanity is just that: talk. It is, if anything, further evidence of his guilt, that she feels that she has to resort to such meaningless talk.

Or, suppose I say that 2 + 2 = 4. Someone says that he would prefer it to be 5, and tries to show that it really can be 5 by saying that: "If we measure two lengths and put them together, then we could find that two point three five units plus two point three five units equals four point seven units; and if we round all those measurements to the nearest integer, so that it is arithmetic, then we get two plus two equals five." Even so, there are such proofs as this: 2 + 2 = (1 + 1) + (1 + 1) = 1 + 1 + 1 + 1 = 4. And note that he only wants 5 because it really is bigger than 4 = 2 + 2. My interlocutor retorts that we have to have axiomatic arithmetic, on pain of paradox (e.g. Cantor's paradox), and that he likes those axioms that let him have 5. Could some paraconsistent logic not give arithmetical axioms the power to give him his 5 as well as us our 4, he wonders; but no, that is not really logic, and axioms that give him 5 are not arithmetical. My interlocutor will not give up though, and he has lots of friends. Even so.

Thursday, March 01, 2018

The Death of Logic

A hundred years ago (more or less) logic died.

It was either Logic and a transcendent creator, or neither,
and atheism was in the ascendant a hundred years ago,
while the God that could be shown (in a logical way) to exist
was not that of the embattled religions of those war-faring days
so it was not even a contender.

Prima facie, logic took off at that time.
We now have lots of formal logics, and they all look very rigorous
because they are very mathematical. They look very scientific.
But, what's so logical about reacting to the Liar paradox by redefining "truth"?
And what's so logical about having each ordinal but not having every ordinal?

Suppose we get a really good String Theory, say "S," one day.
There's no guarantee that we won't need a better theory later,
so why would we use S to redefine all our physical entities?
If the description of electrons in S was E, for example, then
we could replace "electron" with "E," but why should we?
A good reason why we should not is that electrons are electrons!

And arithmetic is a subset of the properties of possible objects:
one object and another object is one-plus-one objects, and so on.
But for a hundred years, science has replaced "1" with "{{}}."
Did not the logician Frege refute Mill's description of "1"?
It turns out that he did not. And he could not have,
because 1 is, basically, Mill's 1 (and Euler's, and yours).

Set Theory mimics mathematics,
so for applications it hardly matters; but,
do the best mathematicians really believe
that 1 is nothing like Mill's 1, is really {{}}?
We all learn what 1 really is at an early age.
{{}} was chosen following Cantor's paradox,
but it also followed that logic had to be replaced.
Logically, there was that paradoxical proof; and
while the Liar paradox is nowadays interpreted
as another reason to replace truth, and its logic,
with something formal, that is not really scientific:
science pursues truth, and logic takes truths to truths
(where to say, of what is, that it is, is to speak the truth).

Tuesday, February 20, 2018

Is Logic Necessary?

I've been looking at Skepticism, following Maddy's 2017, because it connects with the topic of this month's posts: highly evolved apes are unlikely to have a perfect logic, so why should we care if logic gives us paradoxes? We see a tree, we know that it is a tree; that much is ordinary. We cannot rule out its being an alien quasi-stick-insect, of course; but then, we never thought that we had to do that, did we? And now that you come to think about it, don't you think that you could if you examined the tree more closely? Or that some scientists could? Now, we cannot ever rule out the possibility of an error of some kind or other, perhaps an error of a kind that we have never thought about: how could we rule that out? Is that is why the experts on logic think of logic as being formal logics (mathematical models of logic) nowadays? I suppose that experts could be certain about mathematical calculations. However, such logics come with modern definitions of truth, scientific theories of truth, mathematical models of truth, raising the question: What is the truth about truth? The first "truth" in that question is clearly intended to be correspondence truth, but if it does turn out to be the case that the second one cannot be correspondence, then how could the first one be? And if the first "truth" is not correspondence truth, then how satisfying could any answer to any such question be? What if we have, for example, an attractive story about how truth is an attractive story? At the end of the day, we naturally assume that truth is correspondence truth, and that logic is logic, not a mathematical model of logic. Even when it is the experts thinking about the formalities, their metalogic is simply logic; and when they give us theories of their metalogic, they do expect us to think about their presentations of those theories in logical ways. And similarly, we simply assume that trees are not alien quasi-stick-insects of some very convincing kind. We can say that they are very probably not aliens, and then try to justify that "very probably" and maybe wonder why we are doing all of that. But at the end of the day, we are simply such that for us, our logic is necessary. I see a tree, and know that it is a tree. I cannot rule out its being an alien quasi-stick-insect of a very convincing kind, and so my "know" is a sort of gamble: I assume that it isn't an alien. I don't know that it's unlikely to be one (how could I?) but I do know that it's not mad to assume that it isn't one. Since the topic is raised, I admit that it might be an alien, that I don't know that it isn't, that I don't know, in that sense, that it is a tree; but I still claim that I do know that it is a tree, in the ordinary sense. In short, there seem to be at least two senses of "know" in play.

Monday, February 12, 2018

Doppelgangers

It seems to be logically possible for there to be an exact copy of you, say d-you, because it seems that such a thing might exist in a parallel space-time. D-you would be physically and mentally identical to you; but it would not, of course, be you. Now, we naturally assume that none of us have been instantaneously swapped with such doppelgangers. We can never have any reason to think that any of us might have been swapped; but, that is because such swapping would be undetectable, and that is why we cannot rule out the logical possibility of such swapping.

Indeed, you cannot completely rule out the possibility that you are such a doppelganger, because you would have exactly the same memories, exactly the same sense of being yourself. There would be absolutely no empirical difference; the only difference would be semantic: reference intended to be reference to you would fail to be such reference, were it to d-you, for example (and given the falsity of Functionalism, and so forth). And of course, knowledge would be lost, e.g. if I saw d-you at a bus-stop then I would not know that you were waiting for a bus. But of course, I would know that you were waiting for a bus if I saw you at a bus-stop (and you were waiting for a bus). There is no loss of knowledge caused by not ruling out the logical possibility of d-you. We simply assume that such swapping does not happen.

Note that we do not just think it unlikely (and similarly, we do not just think it unlikely that we are brains in vats, or being fooled by demons, and so on and so forth). We do not know for sure that there are no such doppelgangers, and we do not even know for sure that there are unlikely to be any (we can have no evidence for such unlikeliness). But clearly, we are assuming that there are no such things (and nothing else of that rather wide-ranging kind). That is just an obvious empirical fact about our beliefs. (We might not notice it, because being fooled by a demon would be like being a brain in an evil scientist’s vat, and a brain in a vat is like someone having a very long vivid dream; and maybe it is only highly unlikely that you are in a coma right now.)

Thursday, February 08, 2018

Truth in Dreams


In one Cartesian argument for skepticism about the reality of the world, we are to assume that if we were dreaming, then were we to see hands in that dream, those would not be hands. Still, they would be dream-hands, in a dream-world, so dream-reference to them would hardly fail, or would it? If we think of someone dreaming about hands, then clearly those are not real hands; but, were this a dream (not a dream-within-a-dream, which is what our "dreaming" would then refer to), then what is meant by "real hands" within that dream would be dream-hands. You may well wonder if that would be the case, had we fallen asleep having already learnt the meaning of "real hands" in the real world. But presumably we learnt the meaning of "real hands" in this world, and if this was a dream then this world would be a dream-world. You could counter that if this was a dream, then we would still have learnt the meanings of our words in some higher realm, but as soon as we clarify what exactly we are talking about, by describing what we mean by "an external thing," we tie the meanings of our words to this world (the photo is from last year btw :-)

Wednesday, February 07, 2018

Lots of Misprints

I've seen quite a few misprints recently, e.g. in TV text; also top of page 159, and again on page 169, in Maddy 2017 (" 'Proof on ..." instead of " 'Proof of ..."), just before she got to Moore's reason why pointing to each of his hands was a proof that there are two hands (and hence that there are external objects, and hence an external world), which was that he could similarly prove that there were three misprints on a certain page by:
taking the book, turning to the page, and pointing to three separate places on it, saying 'There's one misprint here, another here, and another here'
Maddy 2017: 164 (Moore 1939: 147) Although of course, while that proves that there are three misprints, it does not prove that there are three misprints. And while you might agree with Moore that those were misprints, that would not amount to a proof that they were. Moore, you will recall, does not have to show that there are two hands, nor even that there are two hands, he has to show the externality (so to speak) of such things as hands, given skeptical doubts, which is more like having to prove not just assume, that it is indeed a bad thing to have lots of misprints. And of course, why would we have to prove such a thing! Ask yourself what is meant by "external world" to see for yourself how it exists by definition (and note how one gestures as one does so). And yet, it is precisely that "proof" that is challenged by skeptical doubts (as the above-linked-to review of Maddy 2017 observes).

Tuesday, February 06, 2018

What do Philosophers do?

I'm half-way through Maddy's 2017 (a walk through the modern history of Skepticism), where she describes a weakness of the Argument from Dreaming:
    Although we would not be knowing the world were we now dreaming in the ordinary way, we can rule that out in quite ordinary ways; and whereas we cannot rule out that we are dreaming in some extraordinary way (e.g. a life-long coma), why should we rule it out? Maybe this is a dream-world, and my hands dream-hands within it. But should the fact that I don't know much about the fundamental substance of my hands get in the way of my knowing that I'm typing this with them because they exist (whether that is in a way that is to some unknown world much as dreams are to this world, or in some other way)?

Here's a thought though:
    If some higher power (maybe a UFO) replaced you with a pod-person who was exactly the same as you, physically and mentally, then the people of the world would of course not know, were they to see that person before them, that you were standing there. So, if the underlying substance of the world was such that things were frequently replaced with identical copies, in such ways (and note that we cannot even know that that is unlikely), then our references would frequently fail, and we would end up knowing a lot less about the world than we assume we do.
    We do assume that such does not happen, but that just means that, for example, it is at best epistemic luck that people know that you are there, when they see you. At worst it is knowledge by assumption, because we do assume as much; which reminds me of Wittgenstein's hinge propositions (which Maddy will be getting to shortly). Perhaps we assume that things generally continue to be the same things. Or perhaps we assume that things that look the same are the same.
    I would not say that we know such a proposition, but maybe we do thereby know propositions that depend logically upon it, such as that I have hands. Why not? Knowledge seems not to be some minimal amount of epistemic luck, but rather the sufficient reduction of certain kinds of epistemic luck, as required by one's context; and philosophy is a context with high standards. In philosophy we tend to accept the force of epistemic closure, because the standard is logic.

Friday, February 02, 2018

The Essence of Cantor's Paradox


(1)    There are at least three things

Clearly there are.

(2)    Given some things, there are possible selections from them

E.g. ‘clearly’ and ‘there’ are a pair of words.

(3)    There are all the things given by reiterating (2), given (1)

Note that each possible selection is a thing.

(4)    Given some things, cardinally more selections from them are possible

That is shown by a Cantorian diagonal argument.

(5)    There are cardinally more things of kind (3) than there are things of kind (3)

That follows from (4), given (3), but is contradictory, and hence false.

My resolution begins by observing that apparently timeless possibilities could possibly become more numerous over time. It begins that way because if possible selections are becoming more numerous, then that could easily change the meaning of (3) enough to avoid (5). There is no other way of avoiding the contradiction (the main resolutions were constructivism, with its potential infinities, and going axiomatic, which means not addressing numbers of things directly), which is why this is a paradox.

Consequently this is essentially a proof by reductio ad absurdum that possible selections do become more numerous over time. And how could possible selections become more numerous, if not by a transcendent creator making definitive selections, constructing arithmetic as part of the creation of all things? There is no other way that I can think of; whereas this way is a serious possibility, because
A) mathematicians have taken constructivism surprisingly seriously, and constructivism would only be more Platonistic, and Millian, were the definitive constructions made by a transcendent creator, and
B) theologians have taken the idea of God being beyond our conception of number very seriously, e.g. the Trinity.

Thursday, February 01, 2018

Logic Needs That Hypothesis

In the Germany of the eighteen-nineties, Georg Cantor discovered the mathematical paradox that bears his name.
He put it down to the ineffability of God, even though he was only studying numbers; they were very big numbers.
But, the mathematical mainstream has since then replaced our natural conception of a collection with formal (or fictional) sets that are better behaved.
Whereas, the natural conceptions are fundamental to our actual thinking; in particular, if we cannot rely on our best thinking about formal sets, then why should formal sets be any better?
Consequently logical thinkers need to hypothesize God: only that allows those conceptions without paradox (as previously posted, and as sketched in my next post).
Over the next few posts I aim to scrutinize the elements of this, e.g. the essence of Cantor's paradox, and why we do still need logic in this democratic and scientific age.

Is there a Problem with Prefaces?

Suppose that in the preface to some non-fiction book, the author apologizes for whatever false statements there may be in the book, observing that there are bound to be some, even though each statement in the book is believed to be true by the author. Is this a Preface Paradox? Philosophers often "solve" this problem by taking belief to be sufficiently high credence, so that we would not believe large conjunctions of our beliefs; but of course, our believing each of our beliefs means that we believe them all. Belief is simply not sufficiently high credence (as recently posted). In fact, there is no problem here to solve. And of course, not even a philosopher would ask: Why not say that sets are simply such that sets of beliefs are well-behaved? Could we not have all that we want and nothing that we do not want by putting precisely that much into the axioms of our favourite set theory? No: that is simply not what conjunctions of beliefs are. Nevertheless, that is essentially the mainstream response to Cantor's Paradox (which I shall be posting on in my next few posts). The Preface "Paradox" may not be very paradoxical, but it does show how absurd the mainstream foundations of mathematics are.

Wednesday, January 31, 2018

Mrs Fox's feelings

Basking in the warmth of Heaven, she floats weightless and naked, far far above the factory chimneys and church spires of the world, in the upper reaches of a sultry sky. It's an intoxicatingly fragrant atmosphere, surging and eddying with huge gentle waves of wind and pillowy clouds – nothing like the motionless, transparent oblivion she'd always imagined Paradise would be. It's more like a breathable ocean, and she treads the heavy air, narrowing the distance between her body and that of her man who's flying beside her. When she's close enough, she spreads her thighs, wraps her arms and legs around him, and opens her lips to receive the incarnation of his love.
Michel Faber, The Crimson Petal and the White, 671

Sunday, January 21, 2018

Is very high credence belief?

Imagine holding an almost spherical die with thousands of tiny faces. Each of them is highly unlikely to end up on top when you roll the die. For each face, you have a very high credence in the proposition that it will not end up on top. But when one of them does end up on top, you would not be surprised.
When something that we believe turns out not to be the case, we are surprised. So you did not, for any of those faces, believe that it would not end up on top (you believed that it very probably would not). Very high credence is not belief (despite what many philosophers believe).

I see a red car outside my window, and I can see that its red colour is out there, where the car is. If you told me that the red colour that I was seeing was on the surface of the car, where its paint was, I would not believe you: your saying that would remind me that the red that I see is only in my perception, that it is not actually out there where the car is. Still, I would feel some surprise at that thought, for all that it would be a very familiar surprise. Even though I have a very low credence in the proposition that the red that I see is out there, where the car is, I cannot help believing, each time I look at the car, that its colour is out there. Seeing that it is out there is, at least momentarily, believing that it is out there. That is just the way my perception works. And yours? What about when you look out of a window. Consider any particular arrangement of cars, leaves et cetera that might be outside some window that you could easily get to. Presumably the chance of there being that particular arrangement is very low. You would be surprised if that was the view, were you to look out of that window.
It would be like putting a tiny red dot on one of the faces of that almost spherical die, rolling the die and seeing the red dot on top of it when it stops rolling.
Still, it would also be surprising if you had been able to imagine the view from that window in very much detail before you looked. So, suppose that you go to that window and look through it: you would probably have an unsurprising view. And you could then ask yourself whether you believed, before you looked, that that view was not going to be what you saw. Look now. I think that before you looked, if you did look, you did not believe that you would not have that view. Had you had such a belief, would you not have been much more surprised? Perhaps you were surprised (perhaps, for example, there was a red car there, and you were not expecting there to be one); but even then, your surprise would not, I think, have been like the surprise that we feel when something that we believe turns out not to be the case. It would be less, I think, than your surpise at the red of the car not actually being out there where the car is.
If I believed, of each of that die's faces, that it would not end up on top, then I would believe that none of them would end up on top.
That is how my beliefs appear to me (if I believe that an object is a car, and I believe that it is red, then I believe that it is a red car). How do yours appear to you? Beliefs are what they are, and what they are is not a million miles away from us. We can find out for ourselves what our beliefs are, our particular beliefs, and also beliefs in general (beliefs of various kinds) if we are philosophically inclined, and sufficiently logical. I wonder if philosophers who say that belief is very high credence are confusing belief with a mathematical model of belief.

Friday, January 19, 2018

Turri's Maxwell's Car

When Maxwell arrives at work in the morning, he always parks in one of two spots: C8 or D8. Half the time he parks in C8, and half the time he parks in D8. Today Maxwell parked in C8. It’s lunchtime at work. Maxwell and his assistant are up in the archives room searching for a particular document. Maxwell says, “I might have left the document in my car.” The assistant asks, “Mr. Maxwell, is your car parked in space C8? It’s not unheard of for cars to be stolen.” Maxwell thinks carefully for a moment and then responds, “No, my car has not been stolen. It is parked in C8.”
With that example, John Turri's "Epistemic closure and folk epistemology" post at the Certain Doubts blog began, and he went on to add that:
The epistemic closure principle says, roughly, that if one knows that P, and one knows that if P then Q, and one infers Q, then one knows Q.
Maxwell may have been misapplying logic, when he thought carefully: he recalled that he had parked in C8, rather than D8, and so he thought that his car was in C8 (unless it had, as his assistant noted, been stolen), from which he may have concluded that it was not stolen. (But perhaps he took the low chance of his car having been stolen to be reason enough to think that it had not been stolen. And for all we know the archive's windows looked down on C8.)

Most people think that Maxwell knew that his car was parked in C8 (assuming that it had not been stolen, etc.), but not that it had not been stolen, which contradicts Closure: if Maxwell knows that his car is in C8, and he knows that if his car is in C8 then it has not been stolen (he did seem to know that because he did seem to infer, from it being in C8, that it had not been stolen), then Closure says that Maxwell did know that his car had not been stolen.

Logically, if Maxwell's car was in C8, then it had not been stolen; and the whole point of logic is that logical reasoning takes us from knowledge to knowledge. So it seems to be logical, to go from Maxwell knowing that his car was in C8, rather than D8 (which I think he did know), to Maxwell knowing that his car was in C8 (which most people think he did know), to Maxwell knowing that his car had not been taken out of C8 (which most people think he did not know).

But of course, we can see from this example why that is invalid; and so we also have this insight into why skeptical scenarios are not threats to knowledge (and also why they are). If we are BIVs then we do not have real hands, so how can we know that we have real hands but not know that we are not BIVs? If we are BIVs then we think we have real hands (which is good enough for us BIVs).

Thursday, January 18, 2018

"Know" means know


When people say "I do not think it, I know it," they are usually saying that they are sure of something. And even philosophers regard what they are sure of as knowledge. What if what they are sure of is not actually the case? Well, everyone thinks that what they personally are sure of is the case: that is what it means to be sure of something.
But what if I am sure of something fairly complicated, and you think that what I am sure of is not actually the case. Would you say that what I had was probably some knowledge beyond your powers of understanding? Or would you think it more likely that I had a complicated kind of ignorance?
Almost everyone thinks that a belief must be true if it is to count as knowledge. And philosophers noticed, a while ago now, that there is more to knowledge than certainty and truth:
What if I am sure that it will rain on my parade, and it does. Would you say that I knew that it would rain? Or do you think it more likely that I was just being pessimistic, and unlucky?
For such reasons, philosophers have been debating how they should define "know"; for my thoughts from nine years ago, click on this link. More recently, I have been thinking about scenarios like this:
By the end of the nineteenth century, physicists were sure that, thanks to Newton, they knew the most general laws governing how physical objects move, but thanks to Einstein, our physicists are now sure that those physicists did not know as much as they thought they knew.
Still, it is possible that physicists, in a thousand years time, will discover that it was only some dark ether, or something even stranger, that had made things look Einsteinian. It is possible that those nineteenth-century physicists did, after all, have a lot of knowledge.
Indeed, all sorts of things that we cannot even imagine might be discovered in a thousand years time. The problem is that we can only judge how likely such future discoveries are by using the knowledge that we are now taking ourselves to have. Philosophers are therefore making sure, as best they can, that what they think they know is indeed knowledge:
Philosophers tend to define "know" by constructing axiomatic models of knowledge, so they do seem to be pursuing the truth in a scientific manner (not too dissimilarly, physicists construct mathematical models of physical systems in order to understand them).
But could philosophers pursue the truth about knowledge if they did not already know what truth and knowledge were (note that physicists do not need to know what matter is in order to discover the laws that govern its movements)?
Is there something about truth and knowledge that philosophers do not understand as part of common sense, and cannot come to understand by logical introspection or by asking psychologists, sociologists and linguists?
Well, I suppose that it would be quite mysterious how people could possibly know truths about the world if people were nothing more than highly evolved animals in a purely physical universe. But then, that is why philosophers should not ignore a logical proof that in all likelihood, that is not what we are: logic dictates that in all likelihood, we are incarnated souls (not too dissimilarly, logic dictates that in all likelihood, Fermat's last theorem is true).

Wednesday, January 17, 2018

Gettier's Smith's Job

Smith applies for a job, as does X. Smith thinks that X will get the job, and knows that X has 10 coins in his pocket, so Smith thinks that the man who gets the job will have 10 coins in his pocket. As it turns out, Smith gets the job, and also has 10 coins in his pocket, and so his italicized belief was true. Since Smith was justified in thinking that X would get the job (his new boss had told him that X would get the job) his italicized belief was also justified; but, it was not knowledge, according to Gettier.

One problem with all of that is that it is a bit obscure what exactly is going on: there was a bit of inferring going on, and as a rule we cannot rely on such things as, for example, epistemic closure: If you know that P, and also that P implies Q, then even if you infer Q, you do not necessarily know Q (there was a good example by John Turri at Certain Doubts). Still, one thing is obvious: Smith's reasons for believing the italicized belief were no part of the reasons why it was true, and so it was not knowledge.

However, because those reasons turned out not to be that good (X did not get the job), there is also a question mark over whether they really were good enough to count as justification in the sense required for knowledge (only a question mark). A statement known to be false was always a statement that could have been false (that really could, not just could theoretically). When we think of knowledge we think of statements that can be relied upon, that are justified in ways that basically guarantee their truth.

Sunday, January 14, 2018

Much Knowledge is Epistemic Luck

In a recent post (linked to here) I observed how we simply assume that we can refer directly to the things around us: we cannot know that their substances are not changing in ways that leave their properties the same, because we can only know their properties. Were their substances changing, reference to them would keep failing (assuming that reference is direct).
     And similarly, we cannot really rule out that we are Brains In Vats: all of our evidence is compatible with our brains having been harvested by aliens (in a real world where such aliens are common) and put into high-tech vats that simulate worldly experiences. While we are unlikely to have been harvested recently (as recently noted (although note that we cannot rule out as unlikely a world where are are frequently, but not too frequently, re-vatted)) it is not unlikely (by the standards of the apparent world) that there are such aliens (what is strange is that we see no aliens).
     But of course, we can and do simply assume that there are not such aliens, that we are not currently asleep in our beds and dreaming, that all of our particles are not always being switched with identical particles, and so forth. It is upon such foundations that our knowledge of the external world is built. And of course, we are not BIVs, we are not dreaming, and so on; or at least, I do assume not. And so we do have knowledge of the external world. But, because those are assumptions, such knowledge is epistemic luck.

Saturday, January 13, 2018

Something like Fake Barns

What is adequate justification for holding a belief? It depends on one's context. A true belief that was well-justified when it was formed might cease to count as knowledge within a stricter setting, such as a court-room or a laboratory. And the famous Fake Barns involve unusual contexts. And of course, one needs to be sufficiently rational. Suppose that I see a red car, in a normal road (no fake cars), for example, and so form the belief that there is a red car. But, I also have a lot of irrational beliefs that there are various objects. When there is a red car, I believe that there is, and I am unlikely to have the belief that there is a red car if there is not a red car, although I am quite likely to have some belief that there is something when there is nothing. (It is easy to think of other examples of true beliefs that might seem at first glance to be justified but which do not count as knowledge because they are held by someone who is in some way unqualified.)

Thursday, January 11, 2018

What Do Philosophers Do?

What do you know, for sure? Being sure that you have hands,
for example, could be justified ( you may be using them now,
to operate a phone or a keyboard), but you can hardly rule out
the following scenario, according to which you have no hands:

Your brain was recently harvested by aliens and you are now in a vat
experiencing a detailed simulation; your memories have been altered,
but for you "hand" still refers to things outside the vat. And out there,
those aliens have turned the real world into one enormous brain-farm.

You cannot rule that out,
but you can know that it is unlikely
that your brain was only recently harvested
and so you can, of course, know that you have hands.