X-Message-Number: 19809 From: Date: Thu, 15 Aug 2002 11:04:11 EDT Subject: more on probability --part1_9d.2c681c2e.2a8d1ceb_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Thomas Donaldson insists that probability assessments are impossible or useless in dealing with unprecedented situations, such as revival after cryostasis. This whole discussion is of very marginal relevance, but I'll say a little more anyway. I was amused recently to see a 1996 book, Data Analysis, by Oxford's D.S. Sivia. Apparently the "ideological" split, regarding the foundations of probability theory, still exists that I noted--and resolved to my own satisfaction--about 50 years ago. On the one side are "traditional" or "establishment" statisticians, using mainly Fisher, Neyman-Pearson, etc., and headed in theory by Richard von Mises. To these people, a "probability" is a relative frequency in a sequence of experiments or observations that is infinite, or at least very large. On the other side is the notion of probability as a degree of rational belief, and which can include unique events--past, present, or future--as well as unknown states of nature. Related to this is the Bayes/Laplace formula for *a posteriori* probabilities, which depend in part on *a priori* probabilities which the frequentists would say are unknown or subjective. I have demonstrated--and it's on our web site--that they are both wrong, in part. A correct probability (not "the" probability) of an event is its relative frequency of occurrence in an actual, known, historical sequence, which is another way of saying that it depends on the information available to the observer. The sequence is necessarily finite and the resulting number necessarily approximate. The point is that one can ALWAYS find an appropriate sequence of known experimental results, by sufficiently broadening the criteria, and therefore one can calculate an OBJECTIVE probability for ANY event whatever--even though, in the worst cases, the vagueness or uncertainty makes the exercise nearly useless. An example. Dr. Bob-a-Loo, the shaman, claims he can make it rain in the desert by dancing and chanting. So he dances and chants, and it rains. What are the odds that dancing and chanting can make it rain? The "establishment" types are embarrassed. By their usual methods, since the outcome was very unlikely on the basis of chance, there should now be high confidence in the shaman's power. Of course, the statisticians will try to squirm out of it by demanding much longer than usual odds against chance. But the Bayesians will point out that this is EQUIVALENT to acknowledging a very small *a priori* probability for the shaman's claim--even though the statisticians and the von Mises coterie deny the validity of any such thing as *a priori* probability. Where does my interpretation come in? We don't depend on guesswork or on dogma. We find a suitable, historical sequence of experiments into which the present instance can fit. This could be any of many. An obvious choice might be claims of "paranormal" power. How many such claims have been made (a great many), and how many validated (none). Hence the *a priori probability* was extremely close to zero, and we are not even interested in the outcome. Of course, if the shaman could do it many times in succession, on demand, that would change the picture. Into what sequence might the cryonics question fit? One of them is on our web site--the sequence of technological goals and the results. Look at all the historical goals or projects that might be considered reasonably similar, by sufficiently broad criteria, and the record of successes, continuing efforts, failures to date, and acknowledgements of failure. Try it--you'll like it. Robert Ettinger Cryonics Institute Immortalist Society www.cryonics.org --part1_9d.2c681c2e.2a8d1ceb_boundary Content-Type: text/html; charset="US-ASCII" [ AUTOMATICALLY SKIPPING HTML ENCODING! ] Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=19809