Friday, March 16, 2012

Presentism and future-based theodicies

Suppose that:

  1. There was or is a time t at which God was justified in permitting the then-present horrendous evils of the world only in reference to non-present future goods that God would bring out of them.
For instance, it may be that prior to the Incarnation, God's justification in permitting the evils that then existed involved the Incarnation. Or it may be that many evils are only justified in reference to an afterlife in which they are redeemed and defeated.

For Augustinian reasons according to which evil is but a privation, I am not that sure of (1). But the practice of offering answers to the problem of evil almost always makes significant reference to the future, and this makes me think that (1) is generally taken to be fairly plausible.

Now suppose presentism is true. Then only present goods exist. Imagine that the time t mentioned in (1) is present. Then the present horrendous evils of the world are only justified in reference to future goods, which don't exist. But how can a horrendous evil—say, an instance of truly intense suffering—be justified in reference to something that simply and certainly does not exist? A world that contains horrendous evils and no justifying goods seems to be a pretty bad world, the kind of world that it is hard to see—except on Augustinian grounds that (1) rejects—how God could create it.

Granted, it may be true at t that there will be a justifying good. But is the fact that there will be a good itself a good? Is it a good during the Peloponnesian War that Tolstoy will one day write Anna Karenina? The eternalist can say that during the Peloponnesian War it was true that Tolstoy's writing of Anna Karenina exists. But the presentist cannot say such a thing. Or, more weakly, maybe it is a good thing that a good will eventuate. But the present good of its being the case that a good will eventuate is a shadow of the value of the eventuating good itself. Theodicy is hard enough without one having to use shadows of values.

But perhaps what in general (and not just in the divine case) justifies permitting an evil isn't an actual good, but an likelihood of a good? But the relevant kind of likelihood is epistemic. And if presentism is true, then at t God knows for sure there is no justifying good.

If this line of thought is correct, then a presentist cannot make use of future-directed theodicies. And to the extent that (1) is plausible, a theist should not be a presentist.

Thursday, March 15, 2012

Beauty, observation and objectivity

The following fact is typically seen as evidence for the subjectivity of beauty:

  1. Very long necks look beautiful to the Padaung but not to contemporary Americans.

But the following fact is not typically seen as evidence for the subjectivity of beauty:
  1. Van Gogh's Wild Roses is looks very beautiful by visible light but not so much by x-ray.

Why do we not see (2) as evidence for subjectivity about beauty? I think the answer is simple: Wild Roses is no more meant to be viewed by x-ray light than the Moonlight Sonata is meant to be viewed visually in Fourier transform. Wild Roses and the Moonlight Sonata are intended to be beautiful in those respects that are perceived visually or aurally, respectively, and they succeed admirably at these aims.

We can be a bit more subtle here. A microscopic examination of Wild Roses is not going to reveal the relevant beauty of the work, nor will an auditory examination of the individual notes of the Moonlight Sonata. These works are beautiful in respect of those features that are salient to the appropriately trained "eye" or "ear"—and of course it is not the literal eye or ear that is mainly being trained.

But why not say the same thing about long neck of the Padaung woman, then? She intends her long neck to be beautiful in those respects that are salient to trained Padaung observers. Maybe she is beautiful in respect of her long neck in contemporary North America, too, but we lack the training to make salient to us the features that make her beautiful.

Moreover, it is important to note that the features that make something beautiful may very well be relational features. A part of what can make a work beautiful is precisely the allusions to other works and to the outside world—what makes Anna Karenina a great work of art is in part that the people in it are like real people (which does not mean that every work of literature needs to have people in it that are like real people). Thus it may be that the Padaung woman's long neck is beautiful in part precisely by its relation to particular social practices (and hence when she travels to North America, and is no longer appropriately related to these social practices, she ceases to be beautiful in respect of her neck). Recognizing the aesthetic role of such relations is not a form of subjectivism, relativism or contextualism—it is no more that than recognizing the aesthetic role of the reality of the characters in Anna Karenina makes one a subjectivist, relativist or contextualist.

(Of course, there is also the possibility that the Padaung are simply wrong in their aesthetic judgment. But it is hard to say that without their training. And the possibility of their being wrong is significant evidence for objectivism about beauty.)

[Edited on March 16, 2011, to remove near-contradiction. -ARP]

Friday, March 9, 2012

An account of laws

According to the Lewisian best system analysis of laws, a proposition p is a fundamental law if and only if it is an axiom in the best system. There is room for variation in the concept of a best system, but a standard version in deterministic settings is that the best system comprises only truths and optimizes the brevity of its axioms and the informativeness of its theorems about the world. The biggest problem for me with the best system account is that the fact that something is an axiom in the best system simply does not make it be explanatory.

I think this is a better account. A proposition p is a fundamental law of nature provided that:

  1. p is an axiom in the best system, and
  2. God wills p, as such.

(I am not sure if the will in (2) should be taken to be antecedent or consequent. If miracles are counterinstances to laws, it must be antecedent. But a lot of people think that's a bad account of miracles, and that allows it to be consequent.)

The "as such" in (2) rules out a case where God instead of willing p, wills something that entails p.

This account solves the explanatory problem with Lewis's account by making the fundamental laws be explanatory. They are not explanatory directly because they are axioms in the best system, but rather because God wills them.

Interestingly, I think (1) may imply (2) in the actual world, by divine omnirationality. For that p has the kind of simplicity and fecundity that axioms in the best system are going to have gives God a reason to will p. And since p in fact holds, presumably God willed p. The only exception is going to be if p reports the sort of thing that God has reason to distance himself from. Suppose, for instance, that everyone who is tempted a certain way sins. Then that universal generalization might be a best system axiom, but God has reason not to will it. But in fact it does not seem that any axioms in our world's best system are going to be like that—such regularities don't seem to be far-reaching enough. All the candidates we hear about from physics are propositions that God does not seem to have reason to distance his will from.

If this is right, then in the actual world, all the axioms in the best system are fundamental laws, and Lewis is contingently right. Moreover, this line of thought shows that the fact that p is an axiom in the best system makes it likely that God wills it. Consequently, as long as we know that God exists, we get to keep the epistemological benefits of Lewis's system.

Wednesday, March 7, 2012

Of chocolates and laws

According to David Lewis, the fundamental laws of nature are those propositions that collectively optimize a balance of the twin desiderata of informativeness and simplicity. (You can get maximal informativeness by listing all the facts about the world, at the expense of maximal complexity of description, and you can get maximal simplicity by saying nothing, at the expense of minimal informativeness.) And laws are what follows from the fundamental laws.

But laws are explanatory. While Lewis's laws aren't.

Imagine a finite world w1 which contains a powerful contingent magical being who creates a very large number N of golden boxes, and places a chocolate in each one, to fulfill some aesthetic goal—chocolate goes well with gold. No other explanation of the chocolate content of the boxes exists at w1.

We can ask at w1 why the third golden box contains a chocolate. And the answer is that the magical being put a chocolate in every golden box.

Now imagine a world w2 just like w1 but where the magical being doesn't exist and the boxes and chocolates come into existence ex nihilo. Nothing gets added to w2 that wasn't there in w1. Plainly at w2 there just is no explanation of why the third golden box contains a chocolate.

If the number of boxes N is large enough, the proposition that every box contains a chocolate will be informative enough that it'll be included in the system that maximizes informativeness and simplicity (as N increases, the informativeness of the proposition increases but its simplicity stays constant).

But then if Lewis's account of laws is correct, then at w2 it will be a law that all golden boxes contain chocolates. But laws are explanatory. So at w2 we'll be able to explain why the third golden box contains a chocolate. But we said that at w2 there is no explanation of this!

So the Lewisian account of laws is wrong.

Options: (1) Deny that laws are explanatory. (2) Abandon the Lewisian account of laws. (3) Deny that it is possible to have uncaused chocolates.

I think that (3) by itself won't do, because we can run the argument on a counterpossible. And (1) is unattractive. That leaves (2).

In summary, I think "Lewisian laws" aren't explanatory, and hence aren't laws.

Tuesday, March 6, 2012

Principle of Double Effect as an action-requiring principle

Normally the Principle of Double Effect (PDE) is taken to be a permissive principle: it gives permissibility conditions for actions that are foreseen to have an evil effect. Roughly, the conditions are: the action is not in itself wrong; the evil is not intended as an end or as a means; and the evil is proportionate to an intended good.

Suppose that we adopt the thesis that refraining from an action is itself a kind of action, and that refraining can have effects just as any other action can. Call this the Refraining Parity Thesis (RPT).

Given RPT, it turns out that many of the actions that the PDE is used to justify are actually actions that the PDE actually requires. Suppose, for instance, that dropping a bomb on the enemy headquarters will cause a handful of civilian deaths but the deaths of the military leadership will lead to an early end to the war, saving thousands of civilian lives. Given RPT, consider the action of refraining from bombing. Refraining from bombing (considered maybe as an action of a military commander) has an intended good effect, the saving of the lives of the civilians near the headquarters, and an unintended evil effect, the deaths of thousands of civilians later. It is very plausible that the evil is disproportionate to the good, and hence PDE does not allow one to refrain from bombing.

There will, however, be cases where PDE allows but does not require an action. Suppose that I could save your life by jumping on a grenade. The PDE allows me to jump. The intended effect is saving your life by the absorption of kinetic energy, the foreseen evil is my death, and my death is not disproportionate to saving your life. But refraining from jumping is also permissible. The intended effect is saving my life, the foreseen evil is your death, and your death is not disproportionate to saving my life.

I don't know if RPT is true. I am inclined to think that refraining is not on par with positive action.

Monday, March 5, 2012

Paul Symington on Sophie's choice

Paul Symington has an intriguing post on Sophie's choice, where he defends the thesis that if virtue ethics is right she should have refused to cooperate. I disagree, but I think the post is really worth thinking about.

Saturday, March 3, 2012

Animal consciousness

Sometimes I come up with an argument such that I can't tell for sure if it's more a joke or a really interesting argument. The following is a case in point:

  1. (Premise) If some non-human earthly animals are conscious, all normal mammals are conscious.
  2. (Premise) There have ever been several orders of magnitude more non-human mammals than humans.
  3. (Premise, plausibly a consequence of 2) If all normal mammals are conscious, I should very strongly expect not to experience reality as a human.
  4. (Premise) I experience reality as a human.
  5. So, probably, not all normal mammals are conscious. (By 3 and 4)
  6. So, probably, no non-human earthly animals are conscious.
As for (1), if some non-human earthly animals are conscious, a line must be drawn as to where consciousness is found. There are two main plausible places to draw such a line: (a) humans versus other animals, and (b) animals with sophisticated brains versus other animals. If we draw the line in the second place, all normal mammals will be conscious. As for (2), I don't have data as to how many mammals there are on earth. I saw an unreferenced "400 million" online, and a referenced somewhat smaller estimate for the number of birds (and I could run the argument with birds, too, I think). There are apparently roughly as many rats and mice in the world as humans. And there have been non-human animals for millions of years before there were humans.

I think the difficult philosophical question is whether (3) is true and what sense can be made of it.

I am more inclined to see this argument as a joke, or maybe as a challenge to figure out how anthropic arguments work.

Friday, March 2, 2012

Inductive scepticism and multiverses, theistic and secular

You have a minor ailment. You wonder to yourself if it's going to clear up by itself within a week. Suddenly you receive utterly conclusive evidence that an omniscient and perfectly honest being is speaking with you. Now consider the following case:

  1. The being informs you that there is a twin-earth, where everything has hitherto been exactly like on earth. In particular, twin-earth contains a duplicate of you, whose life has hitherto been exactly like yours. In particular, your twin has the same minor ailment you do. Moreover, the being informs you that exactly one of you and your twin will have their ailment clear up within a week.
The following is clear: at the end of this, you should not be at all confident that your ailment will clear up within a week. I claim that this is still true in each of the following variant case:
  1. Just like (1), except that the being also gives you some additional information afterwards. He tells you that on both earth and twin-earth, superb medical studies of the ailment have been done, and they have concluded that in the vast majority of cases like yours, the ailment clears up within a week.
The additional information about the medical studies is trumped by the information that of you and your twin exactly one will have the ailment clear up. You still should not be confident that your ailment will clear up in a week. Next suppose:
  1. Just like (2), except that instead of the being telling you about the studies, you knew ahead of the communication from the being about these studies in your world, and after the being told you about the twin, you inferred that there must be such studies on twin-earth, too, since twin-earth has up to now been just like earth.
If in case (2) you shouldn't be confident that your ailment will clear up in a week, likewise you shouldn't be confident in case (3). Next consider:
  1. Just like (3), except now the being informs you that there is an infinite number of such twin-earths, and if we let E be the set whose elements are earth and these twin-earths, then on infinitely many members of E, you or your twin (as the case might be) recovers within a week, and on an equal infinity of members of E, you or your twin does not recover.
Multiplying the twin-earths infinitely in this way should still not allow you to be confident that you'll be one of the lucky ones who recovers within a week. Finally, consider:
  1. Just like (4), except that the twin-earths have not been exactly alike, but extremely similar, with any differences being far several orders of magnitude below the ability of our scientific experiments to discriminate between.
This should not make a difference. You still should not be confident of recovering within a week.

Now, if we are justifiably sure that there are infinitely many universes, then we should expect that there are universes that contain near twins like in (5), and we should expect that infinitely many of them your near twin recovers and on an infinity of them your near twin does not recover, and you should not be confident that you'll recover in a week. And if you aren't sure about there being infinitely many universes, but you simply assign a high probability to that hypothesis, then you should significantly lower your confidence that you will recover, below the confidence given by our best medical studies.

This applies to David Lewis's plurality of worlds. It seems to apply to scientific multiverse theories. And it applies to theistic versions of Lewis's theory, like those by Donald Turner or Klaas Kraay, on which only universes worthy of being created exist, since there plausibly is a just as big infinity of worlds worthy of creation where you don't recover in a week as ones where you do. (This is clear if our universe is far enough above the cut-off line that your failing to recover in a week will not push it below the cut-off line. If our universe is too close to the cut-off, then to ensure worthiness, some kind of a compensating good would also have to be present.)

Thus, infinite multiverse theories should sap our confidence in scientific predictions. This is particularly problematic for scientific multiverse theories.

I think the controversial move will be the transition from (3) to (4) actually.

Wednesday, February 29, 2012

Philosophy of cosmology blog

The Templeton-funded Philosophy of Cosmology project at Rutgers has a promising blog.

Sketches towards a theory of quantifiers and quantifier variance

Quantifier variance theorists think that there can be multiple kinds of quantifiers. Thus, there could be quantifiers that range over only fundamental entities, but there could also be quantifiers that range over arbitrary mereological sums. I will call all the quantifiers with a particular range a "quantifier family". A given quantifier family will include its own "for all x (∀x)" and "for some x (∃x)", but may also include "for most x", "for at least two x", and similar quantifiers. I will, however, not include any negative quantifiers like "for no x" or "for at most seven x", or partially negative ones like "for exactly one x". I will also include "singular quantifiers", which we express in English with "for x=Jones". In fact, I will be working with a language that has no names in it as names are normally thought of in logic. Instead of names, there will be a full complement of singular quantifiers, one for each name-as-ordinarily-thought-of; I am happy to identify names with singular quantifiers for the purposes of logic.

Say that quantifier-candidates are operators that take a variable and a formula and return a formula in which that variable is not open. Consider a set F of quantifier-candidates with a partial ordering ≤, where I will read "QR" as "R is at least as strong as Q", and with a symmetric "duality" relation D on F. There is also a subset N of elements of F which will be called "singular". Then F will be a quantifier family provided that

  1. There is a unique maximally strong operator ∀
  2. There is an operator ∃ dual to ∀
  3. If Q is dual to R then it can be proved that QxP iff ~Rx~P
  4. ∃ is minimally strong
  5. If R in F is at least as strong as Q in F, then from RxP one can prove QxP
  6. From P one can prove QxP for any Q
  7. From ∀xP one can prove P (note: open formulae can stand in provability relations)
  8. If Q is singular, then Q is self-dual and Qx(A&B) can be proved from QxA and QxB
We may need to add some more stuff. But this will do for now.

One can set up a model-theory as well. A domain-model for a quantifier family will include a set O of "objects", and a set S of sets of subsets of O, such that if E is a member of S, then E is an upper set, i.e., if a subset A of O is in E, then so is any superset of A as long as it is still a subset of O. A member of S will be called an "evaluator". To get a model from a domain-model, we add the usual set of relations. An interpretation I in a given model for a language with a quantifier family will then involve an ordinary interpretation of the language's predicates, plus an assignment of quantifiers to members of S subject to the constraints that (a) if QR, then I(R) is a subset of I(Q), (b) I(∀) is the evaluator {O}, (c) if Q is dual to R, then A is a member of I(Q) if and only if the complement OA is not a member of I(R), (d) if Q is singular, then I(Q) is a filter-base. We can then define truth under I using the basic idea that QxP is true if and only if the set of objects o such that o satisfies P when put in for x is a member of I(Q) (this should be all done more carefully, of course).

(The interpretation of a name is always an ultrafilter. If we wanted to, we could restrict names to being interpreted as principal ultrafilters, in which case names would correspond to objects, but I think things are more interesting like it is.)

Ideally, we'd want to make sure we have soundness and completeness at this point. I'm basically just making this up as I go along, so there may be a literature on this, and if there is, there will presumably be results about soundness and completeness in it. And maybe we need more rules of inference and maybe I screwed up above. This is just a blog post. Moreover, we might want some further restrictions about how particular quantifiers, like "for most", are interpreted (the above just constrains it to having an evaluator between the evaluators for ∀ and ∃). The point of the above is more to give an example of what a formal characterization of a quantifier family might look like than to give the correct one.

But now it is time for some metaphysics. The notion of a quantifier family is a purely formal one. Moreover, the model-theoretic notion of interpretation that I used above won't be helpful for quantifier variance discussions because it talks of "sets of objects", whereas what "metaphysically counts as an object" varies between quantifier families.

It is easy to come up with quantifier families and perverse interpretations such that under such an interpretation, we would not want to count the members of the quantifier family "quantifiers". Nor would it be a quantifier variance thesis to say that there are many such families and interpretations, since that there are such is not controversial.

I think a Thomist can give an answer: a quantifier family in the formal sense is a bona fide quantifier family provided that the family is analogous to some privileged family of quantifiers, say quantifiers over substances. In other words, the different kinds of existence are defined by analogy to existence proper. This won't satisfy typical quantifier variance folk, as I think they don't want a privileged family of quantifiers. But that's the best I can do right now.

Tuesday, February 28, 2012

Conscience, authority and moral intuition

A former student of mine wrote to me with a query on about how institutional Church authority could co-exist with the authority of individual conscience. She argued that ultimately my conscience will decide whether the authority is to be trusted, and quoted Anscombe as saying that one cannot help but be one's own pilot.

This made me think a bit more about conscience and authority. I had recently been reading about the Charles Bonnet and Musical Ear syndromes. In these, visual or hearing loss, respectively, apparently causes the brain to confabulate visual or auditory data, respectively, to fill in the sensorily deprived blanks. In Charles Bonnet Syndrome, the sufferers see things like colored patterns, faces, cartoons, etc. In Musical Ear Syndrome, they are apt to hear music. The significant thing about both syndromes is that the sufferers are quite sane and fully realize that the incorrect sensory data they are receiving is mere hallucination (that the hallucinations are limited to a single faculty must help there). They may, however, be distressed due to worries that they are insane, particularly if they are misdiagnosed by a psychiatrist, as in a case I recall hearing of.

A reasonable sufferer from one of these two syndromes will accept the testimony of reliable others that what she visually or auditorily perceives isn't there. In so doing, she is genuinely being her own pilot. Indeed, if she were to uncritically accept the visual or auditory data, she wouldn't be being her own responsible pilot: she would be replacing considered judgment with the flow of experience. Likewise, my colorblind son defers to the color judgments of others; an object may look light green to him, but when others testify that it is light pink, he accepts their judgment, and in so doing exercises his epistemic autonomy.

I think something similar can and does happen in moral matters. We have moral intuitions. These moral intuitions can be more or less reliable. But of course raw moral intuitions do not have a final say. Even apart from authority, moral intuitions need to be harmonized. And it may turn out that the best moral theory fitting the bulk of one's moral intuitions can go against some of one's moral intuitions, and then a judgment must be made.

Moreover, there is nothing contrary to being one's own pilot in making a reasonable judgment that a family of one's moral intuitions, or even all of one's moral intuitions, are less reliable than the testimony of an individual or institution one has reason to trust. That is just much an exercise of one's epistemic autonomy as it would be to accept the moral intuitions over that testimony.

I think that sometimes we confuse conscience with moral intuitions. The deliverance of conscience is an all-things-considered judgment of what is morally to be done. It may take moral intuitions into account, but it may also take other relevant data into account as well. The deliverance of moral intuition is not, as such, the deliverance of conscience, though of course in the absence of evidence against the moral intuition, conscience is apt to reasonably accept the content of the moral intuition as true.

It is quite possible for one to reasonably come to the conclusion that one's moral intuitions are less reliable than the teaching of an authority. In such a case, when there is a conflict between one's moral intuition and a teaching of the authority, one's considered moral judgment will at least typically go with the teaching. (I say "at least typically" to leave open the possibility that, say, a particularly strong moral intuition might be judged more likely to be accurate than a teaching that the authority gives quite low weight to.) In so doing, one may very well be a responsible pilot of one's self, if the reasons for accepting the authority as reliable were very good ones.

And one is not going against conscience then. On the contrary, in such a case, it would go against conscience to follow the moral intuitions, because one's considered judgment is that the authority is more reliable than the intuitions.

Our moral intuitions while being a genuine source of moral knowledge are often distorted by the desire to find excuses for our own faults or, more excusably, those of friends. Moral intuitions should not be glorified with the name "conscience". Like a Charles Bonnet Syndrome patient, one can be reasonable in judging that one ought to submit to the judgment of another, and then the other's judgment is the deliverance of one's conscience.

At the same time, I should note that normally our moral intuitions will play a significant role in figuring out that a putative authority should be listened to. When the putative authority's teachings harmonize particularly with those moral intuitions that we take to be more reliable, that will count in favor of the claim to authority, and when they disagree, that will count against the claim to authority. Here I think there is a useful rule of thumb: moral intuitions that something is permissible are less to be trusted than moral intuitions that something is impermissible. An action is impermissible provided there is a conclusive moral reason not to do it. An action is permissible provided that there is no conclusive moral reason not to do it. Generally, perceptions of absence are less to be trusted than perceptions of presence. Moreover, the space of reasons is large, and to judge that none of the infinitely many considerations in that space gives conclusive reason not to do A is fraught witih difficulty. (Of course, judgments about permissibility are very often right, but perhaps only because of the base rate: most actions people perform are right.)

Monday, February 27, 2012

Do riches lead to vice?

This is a fascinating piece on social class and vice. Apparently, either being of a higher socioeconomic class, or seeing oneself as of a higher socioeconomic class, leads to vicious behavior. The article itself says in the abstract: "Mediator and moderator data demonstrated that upper-class individuals’ unethical tendencies are accounted for, in part, by their more favorable attitudes toward greed." So the love of money is a root of at least some other evils, science says.

Consolidating evidence

Here's something that surprised me when I noticed it, though it probably shouldn't have surprised me. The following can happen: My evidence favors p. Your evidence disfavors p. I know you are rational and competent. After talking with you, and consolidating evidence, I rationally increase my evidence for p.

Here's a case. Suppose we have a coin which is either biased 3:1 in favor of heads or biased 3:1 in favor of tails. We don't know which. I have observed a few coin tosses, and they included four tails and seven heads. My evidence supports the hypothesis that the coin is biased in favor of heads. You have observed a few coin tosses, and they were four tails and two heads. Your evidence supports the hypothesis that the coin is biased in favor of tails. Intuitively, I should lower my credence in the heads-bias hypothesis when I learn of your evidence.

But imagine further that the four tail tosses you observed are the same four tail tosses that I observed, but the two heads tosses you observed were not among the seven heads tosses I observed. Then consolidating our evidence, we get four tails and nine heads, which supports the heads-bias hypothesis.

This is humdrum: When we consolidate evidence, we need to watch out for double counting in either direction. The above case makes this striking, because when we eliminate double counting, we get confirmation in the opposite direction to what we would initially have expected.

There is a very practical moral of the above story. It is important not only to remember one's credence in the propositions one believes and cares about, but also the evidence that gave rise to this credence. For if one does not remember this evidence, it will be difficult to avoid double counting (or subtler failures of independence).

By the way, I think it is helpful to think of the disagreement literature as well as discussions about the nature of arguments and other social epistemology stuff as interpersonal data consolidation problems. Getting clear on what we are aiming at should help. You have data, I have data, we all have data. What we are aiming for are methods (algorithms, virtues, etc.) that help us consolidate data across persons to get a better picture of reality than we are likely to have individually.

Moreover, I think that morally speaking it is very important when engaging in argumentation to remember what we are doing: the telos of arguing is to consolidate data across persons in order to get to truth and understanding. This telos is social, as befits social animals. It is not the telos of an argument that I convince you of the argument's conclusion. Rather it is that I convince you of the truth or show you how truth hangs together. If instead of convincing you of the argument's conclusion I convince you by modus tollens of the falsity of one of the premises, and in fact the conclusion is false and so is that premise, then the point of arguing has perhaps been fulfilled. And if in a case where the conclusion is false my argument convinces you of that conclusion, then the argument is a failure qua argument.

Saturday, February 25, 2012

Reasons of trust

Suppose you promise me to do something and suppose I should trust you. Then I have a moral reason not to check whether you did what your promised. Of course, if I have a special responsibility for it, I may also have a moral reason to check. But generally speaking, I think we have an imperfect duty not to check up on people when we should trust them. Moreover, we should trust people unless we have good reason to the contrary. I would be wronging a colleague if, out of the blue, I were to start running his papers through TurnItIn.com to look for plagiarism. Such an action would be a failure to show required trust. It would thus be contrary to collegial love.

Natural love, thus, requires natural faith of us. But our supernatural love for Christ requires supernatural faith of us.

Thursday, February 23, 2012

Infinite lotteries and infinitesimal probabilities

The argument in this post is based on a construction by Dubins (see Example 2.1 here) that I've switched into an infinitesimal case.

Suppose you can have an infinite lottery with ticket numbers 1,2,3,... and each ticket has infinitesimal probability (perhaps the same one for each). Then really weird stuff can happen. Say I toss a fair coin, but don't show you the result. Instead, you know for sure that I will do this:

  • If the coin was tails, I run an infinite lottery with ticket numbers 1,2,3,... and with each ticket having infinitesimal probability
  • If the coin was heads, I run an infinite lottery with the same ticket numbers, but now the probability of ticket n is 2n.
And you know for sure that I will then announce the result of the lottery.

Here's the oddity. No matter what my announcement, you will end up all but certain—i.e., assigning a probability infinitesimally short of 1—that the coin was heads. Here's why. Suppose I announce ticket n. Now, P(n|heads)=2n but P(n|tails) is infinitesimal. Plugging these facts into Bayes' theorem, and assuming that your prior probability for heads was 1/2 (actually, all that's needed is that it be neither zero nor infinitesimal), your posterior probability P(heads|n) ends up equal to 1−a where a is infinitesimal.

So I can rationally force you to be all but certain that it was heads, simply by telling you the result of my lottery experiment. And by reversing the arrangement, I could force you to be all but certain that it was tails. Thus there is something pathological about the infinite lottery with infinitesimal probabilities.

This is, to me, yet another of the somewhat unhappy results that show that probability theory has a quite limited sphere of epistemological application.