> On Monday 28 July 2008 07:04:01 am YKY (Yan King Yin) wrote: >> Here is an example of a problematic inference: >> >> 1. Mary has cybersex with many different partners >> 2. Cybersex is a kind of sex >> 3. Therefore, Mary has many sex partners >> 4. Having many sex partners -> high chance of getting STDs >> 5. Therefore, Mary has a high chance of STDs >> >> What's wrong with this argument? It seems that a general rule is >> involved in step 4, and that rule can be "refined" with some >> qualifications (ie, it does not apply to all kinds of sex). But the >> question is, how can an AGI detect that an exception to a general rule >> has occurred? >> >> Or, do we need to explicitly state the exceptions to every rule? >> >> Thanks for any comments! >> YKY > > There's nothing wrong with the "logical" argument. What's wrong is that > you > are presuming a purely declarative logic approach can work...which it can > in > extremely simple situations, where you can specify all necessary facts. > > My belief about this is that the proper solution is to have a model of the > world, and how interactions happen in it separate from the logical > statements. The logical statements are then seen as focusing techniques. > Thus here one would need to model a whole bunch of different features of > the > world. Cybersex is one of them, sex is another. The statement "Cybersex > is > a kind of sex" would be seen as making a logical correspondence between > two > very different models. As such one would expect only a very loose > mapping, > unless one were specifically instructed otherwise. This puts the > conclusion > at 3 on very shaky ground. Consequently the conclusion at 5 must also be > considered unreliable. (It could still be true.) > > What logicians call logic doesn't bear much resemblance to what people do > in > their day-to-day lives, and for good reason. A logician looking at it > would > argue with almost every step of the argument that you have presented, as > it's > quite ill-formed. (E.g., what does "a kind of" mean?) A biologist would > probably deny that cybersex was sex. So would a pathologist. So this > could > be seen as an example of "From a false premise one can draw any > conclusion". > > N.B.: You called this a fuzzy logic problem, but you don't seem to have > specified sufficient details for such logic to operate. Specifically > which > details are missing varies slightly depending on exactly which version of > fuzzy logic you are considering, but they all require more information > than > is present. Still, I don't think that's the basic problem. The basic > problem is that your "rules" require a large amount of unstated knowledge > to > make any sense...and this is pointed up most clearly by the > statement "Cybersex is a kind of sex". To properly model that statement > would require an immense amount of knowledge. Much, but not all, of it is > built into humans via bodily experience. An AI cannot be expected to have > this substratum of intrinsic knowledge, so it would need to be supplied > explicitly.
This is the kind of analysis I would have made. I would say something like item 2 was just wrong. Cybersex is pretending to have sex while communicating over the internet, and pretending is always different from actually doing. It's quite possible that the word cybersex could mean something different and it would actually be sex, but it doesn't. I don't think using multivalued logics like fuzzy or probabilistic would add so much as getting the meanings more accurate. There are other issues about how different cases modify what things mean and what you might be able to say about it. An example that I like to think of is the supposed fact that birds fly. Well, that's not really a completely true proposition. _Some_ birds fly. One of the special things about birds is that they fly, but not all of them do. If you get a bird from the grocery store, it almost certain won't fly. It'll probably already be dead, for one thing. And even when it was alive, it probably didn't, because it was probably a chicken, or maybe a turkey, though you can get ducks or geese if you're lucky. For me, the thing more helpful than a special multivalued logic is having more knowledge, and an ability to use and manipulate more cases. Even if you use probabilities, you still have to have some system of meaning for the different probabilities to refer to, so you haven't especially saved yourself any work. andi ------------------------------------------- agi Archives: https://www.listbox.com/member/archive/303/=now RSS Feed: https://www.listbox.com/member/archive/rss/303/ Modify Your Subscription: https://www.listbox.com/member/?member_id=8660244&id_secret=108809214-a0d121 Powered by Listbox: http://www.listbox.com
