Talk:Polysyllogism

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	Logic

I removed the "paradox"--it is not composed of categorical propositions and is therefore not logically valid.

I got here from "sorites" shouldn't it be pointed out that sorites are invalid and give examples of those? — Preceding unsigned comment added by 138.88.126.170 (talk) 14:40, 30 September 2011 (UTC)[reply]

Not necessarily a "chain"[edit]

"A sorites is a specific kind of polysyllogism in which the predicate of each proposition is the subject of the next premise. ... Lewis Carroll uses sorites in his book Symbolic Logic (1896). Here is an example:[1]

   No experienced person is incompetent;
   Jenkins is always blundering;
   No competent person is always blundering.
   ∴ Jenkins is inexperienced.

"

This is all very well, but for Carroll sorites was also a game. Invent a sorities and have another logician try to solve it. And the propositions (all assumed to be true) did not have to follow one another so that "the predicate of each proposition is the subject of the next premise."

One of Carroll's puzzles:

   Things sold in the street are of no great value.
   Nothing but rubbish can be had for a song.
   Eggs of the Great Auk are very valuable.
   It is only what is sold in the street that is really rubbish.

Another:

   The only animals in this house are cats.
   Every animal is suitable for a pet, that loves to gaze at the moon.
   When I detest an animal, I avoid it.
   No animals are carnivorous, unless they prowl at night.
   No cat fails to kill mice.
   No animals ever take to me, except what are in this house.
   Kangaroos are not suitable for pets.
   None but carnivora kill mice.
   I detest animals that do not take to me.
   Animals, that prowl at night, always love to gaze at the moon.

As one can see, this gets far more involved than the article suggests. Since I have no idea how to solve these things, even after looking at the source http://www.math.hawaii.edu/~hile/math100/logice.htm someone else needs to update the article. Wastrel Way (talk) 23:19, 27 February 2019 (UTC) Eric[reply]