Goodbye,Descartes

[luckyme]

A few years back a friend recommended "Goodbye, Descartes". I settled in for a good read .. until I reached page 44 and --
"No horned animal is a unicorn."
"All unicorns are horned animals."
-------------------------------
"Some unicorns are not horned animals."

I actually put the book down after that page, thinking that it was a simple equivocation error and not wanting to read a book that slipped into one on page 44 and used it as an example of "Aristotle's error."

I saw a reference to the book recently and now I'm wondering if I was too hasty in not finishing the book.

any opinions? luckyme

[guesswest]

No horned animal is a unicorn
All unicorns are horned animals
------------------------------
Unicorns do not exist


Haven't read this book so can't comment beyond that, but I believe the above is exactly where Aristotle would have finished.

[luckyme]

[ QUOTE ]
No horned animal is a unicorn
All unicorns are horned animals
------------------------------
Unicorns do not exist


Haven't read this book so can't comment beyond that, but I believe the above is exactly where Aristotle would have finished.

[/ QUOTE ]

To be fair to Devlin ( author), he may have been making a decent point with the example, but at the time I didn't want anything to do with any deductions arrived at by treating "animal" as referring to the same entity in both premises.

oh well, luckyme

[cambraceres]

"I admit I used bad reasoning, but it is rubbish all the same"

Albert Einstein talking to Bohr about EPR.

[guesswest]

lucky - can you clarify for me what you mean by 'treating "animal" as referring to the same entity'? Seems to me that's the opposite of what he's doing, restricting one to 'corporeal' and the other to include 'conceptual'.

It's the mixed uses that cause the problem in the first place, if it meant the same in the 1st premise as the 2nd the 1st would be 'some horned animals are unicorns' and there'd be no problem.

[luckyme]

[ QUOTE ]
lucky - can you clarify for me what you mean by 'treating "animal" as referring to the same entity'? Seems to me that's the opposite of what he's doing, restricting one to 'corporeal' and the other to include 'conceptual'.

It's the mixed uses that cause the problem in the first place, if it meant the same in the 1st premise as the 2nd the 1st would be 'some horned animals are unicorns' and there'd be no problem.

[/ QUOTE ]

Yes he used 'corporeal' Animal in one and 'imaginary' in the other and treated them as both as "let animal = A". He was going to illustrate a flaw in Aristotle's syllogisms. When he didn't point out that the 'flaw' is in switching meanings of terms in midstream, I gave up on the book. Yet, the book seems to be taken seriously, so I assume I'm missing something in his claim.

I couldn't see how what he did was any different than "Gretzky wears skates. A skate is a fish. so, Gretsky wears fish."

Mind you, anytime philosophers go through the "Let Entity = E" and then plug it into a logical structure you can end up with some silliness. An entity has qualities that define it, so we can't just take the letters of the word and leave the qualities behind. Gettier problems seem to contain a similar issue.

sorry I wasn't clear, luckyme

[rollyourown]

I don't follow the problem with the argument; it looks perfectly valid to me. Semantically, the two premises are contradictory, so anything follows. Syntactically, by E-conversion, premise 1 becomes 3. No unicorn is a horned animal., which by E-subalternation becomes 4. Some unicorns are not horned animals. Where is the error?
Bruce

[chezlaw]

[ QUOTE ]
Mind you, anytime philosophers go through the "Let Entity = E" and then plug it into a logical structure you can end up with some silliness. An entity has qualities that define it, so we can't just take the letters of the word and leave the qualities behind. Gettier problems seem to contain a similar issue.

[/ QUOTE ]
Don't want to hijack but interested in this. I've started a new thread with a stolen example for you to disect.

chez

[luckyme]

[ QUOTE ]

I don't follow the problem with the argument; it looks perfectly valid to me. Semantically, the two premises are contradictory, so anything follows. Syntactically, by E-conversion, premise 1 becomes 3. No unicorn is a horned animal., which by E-subalternation becomes 4. Some unicorns are not horned animals. Where is the error?
Bruce

[/ QUOTE ]

I posted it to try to sort out what the issue was. It seemed to me that even though taken separately ( ignoring the switch in meaning of 'animal' ) each premise was fine, it made no sense to try and work them together.

"No horned Pugwump is a unicorn."
"All unicorns are horned Gizbobs."

Is how I read his premises. His claim is this structure produces an error on Aristotles part, I couldn't see what the heck Pugwumps had to do with Gizbobs.

You found a route from 1 to 3, ignoring 2.
In the book he combines 1 & 2 using an aristotlian syllogism and comes up with 3 and blames aristotle for the weird result... I guess, I gave up on it when I treated it as equivocation.)

Your spin on it seems fine, but he definitely was off on a different interpretation. Thanks for looking at it, when i get home I'll look it up and see if I can post more of his comments on it.
luckyme

[DougShrapnel]

Does "No horned animal is a unicorn" mean that
1. We have observed every horned animal.
2. All the horned animals we observed were not unicorns?

seems to me that when you add "All unicorns are horned animals."

You either have to say that unicorns don't exist, scratch that, that there is no evidence for the existance of unicorns,or
We have not observed all-horned animals.
Or that some unicorns aren't horned animals.