Arlo, Glen, and Frank, I would like us to come to some sort of common understanding of how to use the word, tautology, because I think the definitional issue is keeping us from making progress on more substantive matters.
See how much of the following you both can agree with: (1) We are talking here about a broad class of reasoning called circular, wherein the conclusion is at least partly determined, not by any facts about the world, but by information stated in the question. (2) A tautology is the most narrowly defined example of such reasoning. In tautology, we already know the answer when the question has been asked. No doubts can be raised. This meaning can be further limited to certain kinds of mathematical expressions. (3) In circular reasoning, (a) the conclusion can be -- at least partly -- worked out from the question because the conclusion contains the question embedded in it but (b) it is not entirely circular, because it also contains other material that is not contained in the question. So, for instance, if the question, "What selection pressure made polar bears white?" the answer "a selection pressure that made polar bears white" is entirely circular. It is a simple repetition of the question as an assertion. But notice that the answer , "A selection for white fur", while highly circular, is not entirely so because it rules out the possibility that the selection was for some correlated trait -- conservation of melanin, say. That information is not entailed in the question. (4) Without trying to settle the question of how many forms of semi-circular reasoning there might be, Lipton and Thompson described a class of semi-circular reasoning called "recursive". (The idea in the name was that the conclusion of the reasoning "runs back" to the question for some of its information. Thus, this part of the explanation is uninformative.) In recursive reasoning, the uninformative part of the explanation is held within a frame that is itself informative. If the question is, "Why is the oil in my car clean?", then the answer, "Because it went through a clean oil filter" is not completely circular but recursive, because the frame, "went through _____ filter" it rules out the possibility that the oil is clean simply because it has not yet been through the engine. The polar bear explanation above is another example of a recursive explanation. "His AIDS symptoms are caused by the AIDS virus" is another. We thought that these recursive explanations play an important role in the development of scientific explanations, because they guided scientists as they collected data that served to revise the frame while keeping the goal of the explanation clearly in view. 4. Now where I am confused is about the relationship between completely circular reasoning and tautological reasoning. The example given at the dictionary of philosophy of a tautology is "Both Paul and Mary were at the meeting; therefore Paul was at the meeting." If this is the type-case of a tautological explanation, then I cannot see why "A selection pressure that made polar bears white" is not another example, given the question, "What selection pressure made polar bears white?" I think at least two of you can help me see where I am going wrong. I think you are going to tell me that I have mixed apples and oranges above, by talking indiscriminately about questions and answers and arguments and conclusions. Can you straighten me out on that? Can you specify the usage community for which your proposed usage is current? Given the FRIAM group, can you suggest a usage convention you would recommend for our further conversation about plurality in scientific explanation? Thanks, Nick -----Original Message----- From: Friam [mailto:[email protected]] On Behalf Of glen Sent: Friday, April 12, 2013 12:39 PM To: The Friday Morning Applied Complexity Coffee Group Subject: Re: [FRIAM] pluralism in science Arlo Barnes wrote at 04/12/2013 11:21 AM: > I thought the tautology is that scientists are trying to converge on > Truth, but Truth is defined as what scientists converge on. I don't think that's (technically) tautology. I've understood that as "begging the question" or assuming your conclusion. It's related to tautology, but weaker, allowing other stuff to participate in the inference process. Tautology is straight equality. Petitio principii can have side effects and other conclusions, of which only one conclusion is equivalent to one assumption. > I would break the cycle by arguing that scientists are not trying to > converge on anything, at least not if they are doing it right. They > would expect that minus experimental error and statistical variation > the results of their experiments would reflect some single coherent > model of reality, even one that we currently have no conception of, > but they are not supposed to and possibly can't assume such. Agreed! ... not if they're doing it right. The trick is how do we know who's doing it right? -- =><= glen e. p. ropella Cause every supersonic jerkoff who plugs into the game ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com
