Monday, October 16, 2006

Certainty and Knowledge: Jonny Blamey

Is there more to knowledge ascriptions than factivity and evidence?
Jack’s dog is dead. Jack got a phone call from the vet saying his dog died this morning. Jack’s evidence is undefeated, (the vet saw Jack’s dog die). Is this enough to determine whether: “Jack knows his dog is dead” is true or false?

Let’s start with a simple definition of knowledge:

S knows that p iff S has a rational degree of belief 1 that p and p is true.

To have a degree of belief 1 that p means that you would accept odds of 1:0 on p. To have a rational degree of belief 1 simply means that you would be rational to accept these odds. The odds are the ratio between the loss if p is false against the gain if p is true. Degree of belief 1 is unique because one can increase the loss indefinitely without affecting the gain. For example, if Jack were to a bet a penny for no gain that his dog was dead, his degree of belief that his dog was dead would be 1. If Jack were to bet £1 million for no gain, then his degree of belief would still be 1. It is perfectly rational to demand more evidence to risk £1 000 000 for no gain than to risk a penny for no gain. Therefore the evidential requirement for a rational degree of belief 1 varies with the size of the stake. Conversely, the evidence alone will not determine whether someone would be rational to have a degree of belief 1. So evidence and truth alone cannot determine knowledge ascriptions.

If certainty is the disposition to rely on beliefs on a loss/no gain basis, then we should expect truthful knowledge attributions to vary with the magnitude of the loss. Is Jack rational to be certain that his dog is dead on the basis of the vet’s phone call? Let us take two situations.

1 : The Dog bed.
Jack decides on the basis that his dog is dead to throw away the dog bed. He has nothing to gain by throwing the dog bed away today. But if his dog is alive, then he will have to get a new dog bed. At this stake size, he is certain that his dog is dead. He is prepared to risk the cost of a new dog bed for no gain. Given his evidence, Jack is rationally certain : Jack knows his dog is dead.

2: The Inheritance.
Jack stands to inherit £1 000 000 conditional on Jack showing that his dog is alive to a lawyer. If he phones the lawyers to tell them his dog is dead, he loses £1 000 000 for no gain. Instead he drives around to the vet to check for himself that the dog is dead on the off chance that there has been a mistake, or that the vet is lying. He is not prepared to risk £1 000 000 for no gain on the basis that his dog is dead. Therefore he is not certain that his dog is dead. Given his evidence he is rational not to be certain. Jack does not know his dog is dead.

11 Comments:

Anonymous Anonymous said...

Jack knows his dog is dead. The vet knows Jack's dog is dead, the question is - does Jack's dog know?

8:46 PM  
Anonymous Jonny Blamey said...

there's only one way to find out

9:32 PM  
Anonymous Curious of Penge said...

Pray tell, Mr Blamey...

7:50 AM  
Anonymous Anonymous said...

Examine its betting behaviour

12:17 PM  
Anonymous Jonny said...

technically speaking, it is irrelevant to the dog that it is dead, because it is dead, so it is undefined what degree of belief the dog has that it is dead.
Unless there is a dog afterlife, in which case it is irrelevant to us whether the dog knows it is dead, since it can impact on none of our actions.
Of course I can't rule out the possibility that there is a dog afterlife and that dogs in dog heaven have a causal impact on us and that by appeasing them we can persuade them to improve our lives. I only occasionally act on this belief, and never when the odds are worse than 100:1.

1:09 PM  
Anonymous Anonymous said...

If the dog was aware of the nature of it's impending demise before it occured, for example it saw the bus that ran it over, in that split second leading up to impact the dog would be able to compute, in it's own mind that taken on the balance of probabilities he would die. The dog would be able to accept death as it knew that impact with the bus would result in it's death - death has to be accepted before it can occur. If the dog did not see the bus then it could not except death without reason and therefore would not know it was dead. Do you see?

9:30 PM  
Anonymous Anonymous said...

apologies for spelling mistake - accept

9:32 PM  
Anonymous curious of Penge said...

Gosh - that's one perceptive dog...

8:06 AM  
Anonymous jonny blamey said...

Not sure if I do see, Mr/Ms Anonymous. You might be saying that whether the dog knows that it is dead depends on whether it accepted its death before its death. By "accept" I presume you mean fully believe. My view is the fact that the dog is dead normally excludes it from knowing anything. There are circumstances where we can meaningfully wonder whether a dead person knows something. Eg I can wonder if my late Grandad knows if my Granny remarried. This would be to assume some kind of afterlife. I do not believe that there is such an afterlife, but even if I did, I would still see no reason to suppose that the dead could only know that they were dead if they accepted it before they died.
Perhaps your point was this: there seems to be a substantive question as to whether the dog knew it would die before it died. It may seem that from my position this is a problem since there is no actual difference to the dogs actions whether it knew or not. But this is to misunderstand my position. I claim that it is a necessary condition for knowledge to be disposed to act in a certain way and for these dispositions to be rational. Dispostions are counterfactual supporting, so it is no problem for the view if someone drops dead without ever having occasion to act on his knowledge. Compare "the stick was brittle" I say that to be brittle is to be disposed to snap in certain situations. It is no argument against this view that there is a substantive question as to whether a stick is brittle just before it is put on the fire.

2:49 PM  
Anonymous Anonymous said...

To clarify - I do not believe in the afterlife - however, take the following scenario - you stay in a strange house, sleep in a strange bed,you wake up in the middle of the night, in the pitch black following a deep sleep - for a fraction of a second you do not know where you are. If you awake in the middle of the night in the pitch black in your own house in your own bed follwing a deep sleep i say you know where you are - almost without having to think. This is true when we consider Jack's dog - if it see's the bus before impact - when it awakes in the afterlife - if there is such a thing it will be aware in its subconcious that a bus had hit it and therefore would know it was dead instantly. This is a similar scenario to the one detailed above when you awake in your own house. If, however the dog did not see the bus before impact when it awakes in the afterlife it would not know that it was dead as detailed in the second scenario. If it did not know it was dead at this point it never will therefore does Jack's dog know it is dead? Do you see?

7:07 PM  
Anonymous jonny blamey said...

Mr/Ms Anonymous, it strikes me that this discussion is incurably speculative. It seems we both concur that there is no afterlife, yet we appear to be discussing under what conditions a dog will know whether it is dead given that there is an afterlife. To take Curious from Penge's comment into consideration, it is not entirely straightforward whether your average dog has the conceptual apparatus capable of such knowledge. Come to think of it, I am not even sure if I do: one thought that has been bothering me is that if there is an afterlife, then surely Jack's dog is NOT DEAD, otherwise it would be called the after death. The whole point about the afterlife is that you live on after what appears to be your death. If this is the case, then it is impossible for Jack's dog to know he is dead because he is not dead. It would be interesting to ask a vigourous Christian whether Jesus knows that he is dead, just as a point of reference.
The waking up in a strange room/well known room comparison I don't see I'm afraid.

10:38 PM  

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