cpshelley@violet.waterloo.edu (cameron shelley) (06/27/91)
In article <1991Jun26.152830.12273@cis.ohio-state.edu> byland@iris.cis.ohio-state.edu (Tom Bylander) writes: [...] >I should mention that I do not believe that logic is going to solve >all the world's problems. As many articles have noted, there are lots >of problems with logic. However, just because logic has some problems >doesn't mean that logic is dispensable. Whether we like it or not, >modus ponens is still something we will have to take into account. Curious you should metion modus ponens. At the CUNY Cog. Sci. conference this year, there was a session given by a panel of philosophers on the subject of the psychological reality of some classical rules of logic. They gave some interesting statistics on when a group of university students actually performed inference in problems where it was possible. Modus ponens was more readily used than modus tollens, among other things. However, they also gave some counter-examples to the use of modus ponens, which I don't presently have at hand. Perhaps some interested reader can fill me in again. If correct (and apparently the 'validity' of classical inference is currently a hot debating point among philosophers concerned with such things) then the account of modus ponens you're looking for may not be as simple as A -> B A ------ B in all situations. Whatever logic does do (or model) in producing interesting behaviour, it doesn't appear to be enough. Cam
silber@orfeo.Eng.Sun.COM (Eric Silber) (06/27/91)
Question: If formal logic is viewed as a characterization of a particular type of communication/negotiation among a multitude of "agents" which compose a reasoning system, then can formal constructs like "A->B , A, therefore B", be seen from the standpoint of a communication "paradigm" (sic) which accounts for the "fuzziness" of actual human "reasoning" through a theory of faulty transmission, interference etc? (i.e. a predicate logic in which implication involves some kind of communication between predicates (rather than some kind of set theoretical operations on them?)
minsky@media-lab.media.mit.edu (Marvin Minsky) (06/27/91)
In article <1991Jun26.173142.3060@watdragon.waterloo.edu> cpshelley@violet.waterloo.edu (cameron shelley) writes: >In article <1991Jun26.152830.12273@cis.ohio-state.edu> byland@iris.cis.ohio-state.edu (Tom Bylander) writes: >[...] >>I should mention that I do not believe that logic is going to solve >>all the world's problems. As many articles have noted, there are lots >>of problems with logic. However, just because logic has some problems >>doesn't mean that logic is dispensable. Whether we like it or not, >>modus ponens is still something we will have to take into account. > >Curious you should metion modus ponens. At the CUNY Cog. Sci. conference >this year, there was a session given by a panel of philosophers on the >subject of the psychological reality of some classical rules of logic. >They gave some interesting statistics on when a group of university >students actually performed inference in problems where it was possible. >Modus ponens was more readily used than modus tollens, among other >things. However, they also gave some counter-examples to the use of >modus ponens, which I don't presently have at hand. Perhaps some interested >reader can fill me in again. > [...] Whatever logic does do (or model) in producing interesting >behaviour, it doesn't appear to be enough. > > Cam I'm glad Cam mentioned this, because I was having trouble explaining why I seemed to be so much against "logic" or "formalism" or whatever it was, and a lot of pro-philosophical readers seemed disturbed at this. And well they might be, because perhaps what I really meant to say was not so much that logic was bad but that the general direction of philosophy itself may be too psychologically naive. What Piaget discovered, more or less, was that children of even 10 to 12 years old are still generally both not disposed to, and apparently, not very well able to, use any of the traditional forms of logical inference. Nor, in fact are most adults, except when the problems are handed to them in the simplest (unidirectional) forms. And yet, my friends, it is easy to lose an argument with a 10 year old. Or even a five-year old, when you're wrong enough.
dirish@csc-sun.math.utah.edu (Dudley Irish) (06/27/91)
In article <1991Jun27.005850.1176@news.media.mit.edu> minsky@media-lab.media.mit.edu (Marvin Minsky) writes:
From: minsky@media-lab.media.mit.edu (Marvin Minsky)
And well they might be, because perhaps what I really meant to say
was not so much that logic was bad but that the general direction of
philosophy itself may be too psychologically naive.
I am curious as to what leads you to say that the general direction of
philosophy may be to psychologically naive. Could you please expand
on this comment?
--
Dudley Irish / dirish@math.utah.edu / Manager Computer Operations
Center for Scientific Computing, Dept of Mathematics, University of Utah
The views expressed in this message do not reflect the views of the
Dept of Mathematics, the University of Utah, or the State of Utah.sarima@tdatirv.UUCP (Stanley Friesen) (06/28/91)
In article <1991Jun27.005850.1176@news.media.mit.edu> minsky@media-lab.media.mit.edu (Marvin Minsky) writes: > What Piaget >discovered, more or less, was that children of even 10 to 12 years old >are still generally ... not very >well able to use any of the traditional forms of logical inference. >Nor, in fact are most adults, except when the problems are handed to >them in the simplest (unidirectional) forms. Indeed, it has been my observation that nobody ever uses traditional logic to 'reason' unless they have been *trained* to do so in school. This kind of reasoning (modens ponens &c.) is simply alien to normal human thought patterns and must be 'forced' to be used at all. That is, human reasoning does not normally take the form of 'if X then Y', rather it takes the form of 'X is like Y, Y has property a, assume X has property a'. Now, the question becomes, can 'reasoning' based on free-association and analogy-based filtering be adequately captured in any formal system that can be reasonably called 'a logic'. [Of course if *any* formal system is considered to be 'a logic', then we must ask whether asssociative reasoning is essentially formal (in this sense)]. -- --------------- uunet!tdatirv!sarima (Stanley Friesen)
minsky@media-lab.media.mit.edu (Marvin Minsky) (06/28/91)
In article <DIRISH.91Jun27122456@csc-sun.math.utah.edu> dirish@csc-sun.math.utah.edu (Dudley Irish) writes: >In article <1991Jun27.005850.1176@news.media.mit.edu> minsky@media-lab.media.mit.edu (Marvin Minsky) writes: > > From: minsky@media-lab.media.mit.edu (Marvin Minsky) > > And well they might be, because perhaps what I really meant to say > was not so much that logic was bad but that the general direction of > philosophy itself may be too psychologically naive. > >I am curious as to what leads you to say that the general direction of >philosophy may be to psychologically naive. Could you please expand >on this comment? > >-- >Dudley Irish / dirish@math.utah.edu / Manager Computer Operations >Center for Scientific Computing, Dept of Mathematics, University of Utah > >The views expressed in this message do not reflect the views of the >Dept of Mathematics, the University of Utah, or the State of Utah. I mean that they don't seem very good at observing how minds work. It was Galton, Freud, Piaget, Tinbergen, etc., who had good ideas about thinking or so, and I find it hard to think of good contributions from philosopher types. When I've mentioned this to educated people, I usually get the reply that, "yes, but they would not have had those ideas, but for the tradition of Hume, Descartes, Kant, etc." My inclination is to wonder why psychology did not begin to flower until the late 19th century, and one conjecture is that it could have been delayed by the influence of the naive minimalist philosophers. But this is only a casual impression. I don't claim any authority on the history of those ideas.
petersja@debussy.cs.colostate.edu (james peterson) (06/29/91)
In article <69@tdatirv.UUCP> sarima@tdatirv.UUCP (Stanley Friesen) writes: > >This kind of reasoning (modens ponens &c.) is simply alien to normal human >thought patterns and must be 'forced' to be used at all. > >That is, human reasoning does not normally take the form of 'if X then Y', >rather it takes the form of 'X is like Y, Y has property a, assume X >has property a'. > >Now, the question becomes, can 'reasoning' based on free-association and >analogy-based filtering be adequately captured in any formal system that >can be reasonably called 'a logic'. [Of course if *any* formal system is >considered to be 'a logic', then we must ask whether asssociative reasoning >is essentially formal (in this sense)]. >-- Isn't the real issue here whether formal reasoning can be captured by your "free-association and analogy based filtering" and not the other way round? I don't mean to put this as a chicken and egg dilemma, but if, as this thread suggests, the "natural" mode of reasoning is *not* formal, then it seems that formal reasoning must be predicated upon this inferential style of reasoning as, perhaps, a kind of specialization, or abstraction. If this is the case, namely that formal reasoning is "built up" out of non-formal, "natural" reasoning, then it must be possible to give an account of how the inferential form can give rise to formal kinds of reasoning. In the background, it seems to me that such an account would also explain something of the nature of science in general (as well as how such a thing as science is possible for creatures such as us). james sends. -- james lee peterson petersja@CS.ColoState.edu dept. of computer science colorado state university "Some ignorance is invincible." ft. collins, colorado (voice:303/491-7137; fax:303/491-2293)