Poodles

[don1]

All poodles are dogs but not all dogs are poodles

what does this refer to?

[Grunty]

Someone is probably making the point (in his or her opinion) that poodles are better than the average dog.

[dr john]

At a slightly more intellectual level, in deductive reasoning these are parts of a syllogism.

http://en.wikipedia.org/wiki/Syllogism#Everyda y_syllogistic_mistakes

[heathfield]

Rottwielers don't make good lapdogs.

[don1]

Dr. John at my age I wont live long enough to take a degree course, what does it mean in idiots terms?

[Tiny E. A]

Also Dr John, in the reference used on wikipedia, you could place A as dogs, B as poodles and C as white, which would then make the initial statement true, not false as it is with the examples wikipedia have used. How are you meant to know which examples you should use and which you shouldn't? I'm baffled.

[dr john]

Sorry folks. The basic principle is that just because all members of Group A are members of Group B, it doesn't automatically follow that all members of Group B are members of Group A. (There are some dogs that aren't poodles.)
To argue that all dogs are poodles is a logical fallacy.

[Tiny E. A]

But in reference to the wikipedia example it would be true to say,

some dogs are poodles, some poodles are white and therefore some dogs are white.

and wikipedia point out it is false to say,

some cats are black, and some black things are televisions, therefore some cats are televisions.

Both these follow the principal, some A are B, some B are C and therefore some A are C. But in one case it is true and in another it's not. It's therefore impossible to decide whether the principal is true or unntrue, it depends what words you choose to replace the letters with.

[don1]

is it reasonable to say in layman's terms that all of the above is claptrap?

I have a black TV set and my wife has a black cocker spaniel which will give me better reception when the cup final is on?

[Tiny E. A]

ha ha don1, I think you're probably right.

[Peter Pedant]

It is referring to the fallacy of the undistributed middle term.

in the wiki article you will find that discussed in general terms at the bit that begins,

everyday syllogistic mistakes.

Wiki discusses sentence logic - and I have to say there are better discussions around.

[Peter Pedant]

wiki gives as a reference

Copi Introduction to Logic - that's quite good

Nowadays the stress is on first and second order logic, first do Copi and if you like that, then try to get your head around Boolos and Jeffrey now selling well in its third edition or Cutland - but honestly you have to have a stomach for this sort of thing.