Hi Peter, Good questions.
On Sun, 19 Oct 2003, Peter Tillers wrote: }1. Are the following two separate responses by Charles Twardy and Joseph }Halpern to Lotfi Zadeh consistent?: } [Halpern says causal modeling supports degree of responsibility but not } degree of causation, while Twardy says it supports degree of } causation as well.] I think we just chose different aspects, and that your reconciliation worked pretty well. But I think another main difference is whether you use the framework to answer questions of actual or "token" causation which is more about assigning responsibility (What caused the fire?), or whether you use it to answer questions about general or "type" causation (Does smoking cause lung cancer, in general?) Halpern's work with Pearl (that I know) has concentrated on actual or token causation. Either C contributed to E or not, but not all causes of E contributed equally. (They also analyze what it means for a set of causes to be "the" actual cause.) Work on general causation (most of Pearl 2000) is more clearly a matter of degree: C causes E if there is some state of the model where C can affect the probability distribution on E. (Or, if you want to talk about particular states rather than variables, you may distinguish promoting from preventing.) One other issue: you can use the framework and still believe in determinism (as I think Pearl does). Then the probabilities are either uncertainties about the exogenous variables or the models. Pearl and Halpern assume determinism for actual causation. But the general framework does not need to make that assumption. -Charles -- Charles R. Twardy, Res.Fellow, Monash University, School of CSSE ctwardy at alumni indiana edu +61(3) 9905 5823 (w) 5146 (fax) "Incongruous places often inspire anomalous stories." -- S.J. Gould
