Peter, since I've already flooded the list with causality messages, I'll
keep this one brief: It may make sense to talk about the causal
relationship between X and Y, but just giving the frequency information
is not enough to determine the causal relationship. (For exmaple, X and
Y may have a common cause.) If we have a good model of causality, then
we can make sense out of a statement like "there is a probability c that
X caused Y". However, to make sense of it, I would argue you need a
probability over causal models. (Roughly speaking, "X caused Y" becomes
a random variable over causal models.) I'm not quite sure what it would
mean for you that "Y's contribution to the occurrence of X is m/n", but
this seems related to the notion of responsibility that Hana Chockler
and I talk about in our paper. (Note, however, that while degree of
responsibility is a number between 0 and 1 in our definition, it does
not act like a probability.) Finally, for what it's worth, I'm happy to
try to bridge the "two cultures" problem to the extent that I can.
- -- Joe
Peter Tillers wrote:
> A na�ve question from a law teacher who does not specialize in (even)
> causality in law:
>
> On the issue of the bivalency or non-bivalency of causation or of bivalent
> or non-bivalent talk about causation, suppose:
>
> ***
>
> Y happened
>
> then (�almost immediately thereafter�)
>
> X happened
>
> X is a recurring or replicable event; the same is true of Y and Z
>
> if Y, the frequency of X is .6 � because [but am I begging one question
> here?], as it turns out, if Y, the frequency of Z = .5; if Y + ~Z, the
> frequency of X is .4; and if Y + Z, the frequency of X is .8
>
> and
>
> if ~Y, the frequency of X is 0.2; but if ~Y, the frequency of Z is unknown
>
> ***
>
> How � if at all � should we talk about the causal relationship between X
> and Y?
> Do we need to talk about Z to do so?
>
> More important {?} (for present purposes), if we think it does makes sense
> (in this situation) to talk about the causal relationship between X and Y,
> does it matter whether we try to state our conclusion as
>
> �there is a probability c that Y caused [as defined] X�
>
> or instead
>
> �Y's contribution to the occurrence of X is m/n�
>
> Does the answer to the last question (and also to the earlier questions?)
> depend on whether or not our causation-talk is part of an endeavor to find
> the best possible causal account of the occurrence of Y or whether, instead,
> we are just trying to figure out what action or actions [other than further
> research] to take given our present state of knowledge?
>
> Does the question of what sort of causation talk makes sense ultimately
> depend only on one's ontology, on one's theory of how, e.g., prior states
> influence subsequent states [or, more generally, how one state influences
> another], and also, perhaps, on the question of whether there is one
> ontology or many; i.e., on whether ultimately it must be the case [or not]
> that all ontologies are reducible to a single ontology � a single theory of
> the {workings of the} cosmos {and everything in it} �, one in which
> causality works in some specified fashion? [The last question prompts the
> thought that perhaps we will not have and cannot have a comprehensive theory
> of causality until and unless we have a comprehensive account of phenomena
> in the cosmos � which may be to say: �never.�]
>
> ***
>
> BTW: It is not a new insight to say that part of the reason for the
> confusion in law about �its� meaning of causality is lack of clarity in the
> law about whether [or when] the law, in speaking of causality, is referring
> to its own distinctive [and possibly "non-scientific"] notion of causality
> or whether [or when] the law, in using causation talk, means to refer to or
> borrow some �external� notion of causality, such as a �scientific� notion of
> causality. [It would be of little comfort for many judges to discover, were
> they to so discover, that in �science� there is quite a diversity of notions
> of causality. The legal response to this chaos (or multiplicity) might well
> be to adopt a legal definition of matters such as �physical causation.� But
> such a legal response is likely to make it ever more difficult for the legal
> community and the scientific community (-ies) to understand each other.]
>
> Postscript: I will read _everything_ Joseph Halpern pens about legal
> causation. I promise! In exchange, however, he must promise to help me to
> understand what he has written. (There is this persistent "two cultures"
> problem. See C.P. Snow.)
>
> pt
>
> *****
>
> Peter Tillers http://tillers.net
> Professor of Law
> Cardozo School of Law, Yeshiva University
> 55 Fifth Avenue, New York, NY 10003
>
> (212) 790-0334; FAX (212) 790-0205
>
> [EMAIL PROTECTED]
