If 1 co-occurs with 2 50% of the time, and 2 co-occurs with 3 50% of the time, and that 1 never occurs with 3 except when 2 has occurred, then: * Given 1 happens, then you would guess that 3 will happen 25% of the time. * But if you knew whether or not 1 had caused 2 in a particular instance, you could significantly improve that guess (shifting to 0% or 50%). * In contrast, if you knew 2 happened, you would guess that 3 would happen 50% of the time, AND it wouldn't change anything if you found out whether or not 1 had happened. <echar...@american.edu>
Now, in place of "co-occurs" some people want to substitute "cause", which is frustrating and confusing to you, because you are an experimentalist. This is an "observational" approach to trying to draw conclusions, not a "true experiment" approach. At no point do you get to manipulate the variables and see what happens. You *just *look at the data that was collected, and conclude A) that 2 causes 3, and B) that to the extent that 1 causes 3, it causes 3 via 2, and in no other fashion. And, as an experimentalist, you know that's a pretty non-ideal approach to getting at causation, no matter how schmanzy the algorithms get. In contrast, let us imagine we are studying the vocalizations of macaques, and we notice that a certain vocalization happens, which haven't heard very often, seems to co-occur with the presence of leopards. We think "Hey, maybe seeing a leopard is causing the cries" ---> Presence of leopard causes seeing of leopard, seeing of leopard causes cries. In this case, we would find that a much messier relationship. It would look something like this: * Presence of a leopard co-occurs with seeing a leopard 80% of the time. * Seeing a leopard co-occurs with cries 80% of the time. * IF seeing the leopard screened off, then when a leopard is present, you would expect a given macaque to make a cry 64% of the time - if, and only if, they see the leopard. * But you observe a much higher rate of response when you do your observations. What's happening? Why is the leopard-call response not "screened off" by having seen the leopard? * Well.... there are OTHER ways that the presence of a Leopard causes cries, such as hearing a leopard, or smelling the leopard. (Plus leopard calls are mimicked.) Because of that, it wouldn't be surprising to have leopard calls occur 80 or 90% of the time a leopard is nearby. On Sat, Dec 4, 2021 at 7:38 PM Nicholas Thompson <thompnicks...@gmail.com> wrote: > Frank, > > Still need help. Given events 1, 2, and 3, 3 has been screen off by 2 from > 1, if the probability that 3 occurs given that 2 has occurred is equal to > the probability that 3 occurs given that both 2 and one have occurred. > As I understand mathematics this equality requires that the probability of > 1 occurring is 1.00. Another way to say that is that the probability that > 3 occurs if 2 has occurred is the same as the probability that 3 has > occurred if 2 has occurred, and 1 has already occurred. What's the fun in > that? In other words, given the possibility of other causes for 2, the > fact that 2 occurs gives us relatively little evidence that 1 has > occurred. Isn"t this true of all causal abduction? > > N > > .-- .- -. - / .- -.-. - .. --- -. ..--.. / -.-. --- -. .--- ..- --. .- - . > FRIAM Applied Complexity Group listserv > Zoom Fridays 9:30a-12p Mtn UTC-6 bit.ly/virtualfriam > un/subscribe http://redfish.com/mailman/listinfo/friam_redfish.com > FRIAM-COMIC http://friam-comic.blogspot.com/ > archives: > 5/2017 thru present https://redfish.com/pipermail/friam_redfish.com/ > 1/2003 thru 6/2021 http://friam.383.s1.nabble.com/ >
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