Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!laura From: laura@utzoo.UUCP (Laura Creighton) Newsgroups: net.sci,net.philosophy,net.misc Subject: Re: science and belief Message-ID: <4150@utzoo.UUCP> Date: Sun, 29-Jul-84 14:07:02 EDT Article-I.D.: utzoo.4150 Posted: Sun Jul 29 14:07:02 1984 Date-Received: Sun, 29-Jul-84 14:07:02 EDT References: <2980@ecsvax.UUCP> Organization: U of Toronto Zoology Lines: 56 This ``absence of evidence is not evidence of absence'' bit: I think that it is only one way of stating that it is not possible (in the general case) to prove a negative. The best way to try to prove a negative is to set something up which goes: p implies not-q q therefore not-p (Try to prove that my class is not full of 7-up. glass full of 7up implies glass not full of coke glass full of coke, therefore glass not full of 7up) Now the way that you would like to set this up to prove that PSI does not exist is: existence of PSI implies some sort of physical evidence no physical evidence therefore no PSI You notice that the form of the argument, (Denial of the Consequent) is the same. However, in the first example I could point to the existence of something and conclude from that. Here I am stuck with trying to prove ``no physical evidence'' which is a tougher proposition. Even if there has been no evidence whatsoever, there is always the possibility that there will be some tomorrow. However, we cannot all make like the Red Queen and believe 7 impossible things before breakfast. At some point you need to set a threshhold and say ``unless there is more than this much evidence I am going to assume for the moment that not only is there none but there isn't going to be any either.'' Of course, having done this you have to remember why it is that you are disbelieving something so that if somebody comes by with a heck of a lot of evidence that goes over the threshhold then you will reexamine the evidence. This is necessary. Otherwise I will have to keep thinking that ``there might be a big hairy monster in my sock drawer that eats my socks -- even though I haven't seen it (yet)'' and anything else I could possibly imagine. To balance this problem is the generally accepted claim that the people who are trying to present a new theory have to provide the evidence. And if the claim is extrodinary, then then evidence had better be extrodinary as well. It may be that there is extrodinary evidence for PSI that we either don't know how to recognise yet, or haven't found for some other reason. But, until the people who are interested in such things actually present this evidence, there is no more reason to believe in PSI than there is to believe in my sock monster. Laura Creighton utzoo!laura