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A logic question...need help!

TheMadFool August 01, 2017 at 07:22 14625 views 30 comments
@andrewk@Nagase or anyone else.
Premise 1: All living things are things that suffer
Premise 2: No living things are things that want to suffer

I drew a Venn diagram and no conclusion seems to follow.

I even tried some backward thinking, like so:

Since there's a negative statement (premise 2), the conclusion must be negative.

There are only two negative categorical statements:

A) No S are P
B) Some S are not P

It can't be B from the Boolean perspective because B's a particular statement and can't be derived from universal statements.

So, it has to be A: No S are P. The middle term in the premises is = living things. So, the conclusion must be:

No things that want to suffer are things that suffer. But the Venn diagram doesn't show this conclusion.

What's wrong? Thanks.

Comments (30)

Michael August 01, 2017 at 07:58 #92110
Wouldn't the "things that don't suffer" and "things that want to suffer" circles overlap? So the "things that want to suffer" and "things that suffer" circles would be fully apart. So the Venn diagram does show your conclusion.
TheMadFool August 01, 2017 at 08:28 #92116
Reply to Michael I don't understand your point. Let me give you another example:

1) All cats are mammals
2) No cats are dogs

What is the conclusion?

Draw a Venn diagram in the standard way and you'll see we can't draw any conclusion from it. Strange??!!
Michael August 01, 2017 at 08:36 #92121
Reply to TheMadFool I suppose the difference with that example is that it doesn't include the tacit premise that only cats are mammals, whereas the first example does include the tacit premise that only living things are things that suffer, being that it doesn't seem to make sense for there to be suffering non-living things.
TheMadFool August 01, 2017 at 08:47 #92129
Reply to Michael The answer's still not clear. Can you rephrase it in standard form.
Michael August 01, 2017 at 08:57 #92134
Reply to TheMadFool You've already given the conclusion: No things that want to suffer are things that suffer. I'm simply pointing out that you can see this from a Venn diagram if you draw one. Given that all and only living things suffer, the "living things" and "things that suffer" circles will effectively be the same circle. And given that no living things want to suffer, the "things that want to suffer" circle will be outside the "living things" circle, and so therefore outside the "things that suffer" circle. No things that want to suffer are things that suffer.
Srap Tasmaner August 02, 2017 at 23:20 #92524
Reply to TheMadFool
Syllogisms from Orphan Black (you have to answer true or false):
Some bags are pockets, no pocket is a pouch.
Conclusion: All bags are not pouches.

Some pigs are predators, no predator is a pet.
Conclusion: Some pigs are not pets.

Some maggots are flies, no fly is welcome.
Conclusion: no maggots are welcome.

Some doctors are fools, all fools are rich.
Conclusion: Some doctors are rich.

All mangoes are golden, nothing golden is cheap.
Conclusion: All mangoes are cheap.

Then there's Dodgson/Carroll:

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;
Conclusion: Animals, that prowl at night, always love to gaze at the moon.
TheMadFool August 03, 2017 at 08:01 #92667
Quoting Srap Tasmaner
Some bags are pockets, no pocket is a pouch.
Conclusion: All bags are not pouches


Invalid, fallacy of illicit minor

Quoting Srap Tasmaner
Some pigs are predators, no predator is a pet.
Conclusion: Some pigs are not pets


Valid

Quoting Srap Tasmaner
Some maggots are flies, no fly is welcome.
Conclusion: no maggots are welcome


Invalid, fallacy of illicit minor

Quoting Srap Tasmaner
Some doctors are fools, all fools are rich.
Conclusion: Some doctors are rich


Valid

Quoting Srap Tasmaner
All mangoes are golden, nothing golden is cheap.
Conclusion: All mangoes are cheap.


Invalid, the conclusion should be negative since one premise is negative.

What's your point though? Did you have a look at the premises in the OP. It seems we can't draw any conclusion from it. Can you help?
Srap Tasmaner August 03, 2017 at 18:31 #92764
Reply to TheMadFool
No point. You're on a logic kick, and I think it's cool that the sort of syllogisms you're messing with have recently been featured in a TV show (an excellent TV show). And one needs no reason to quote Lewis Carroll.

As for the OP, I thought that was settled. Were you expecting something else?

ADDD: You could conclude with Freud that all living things possess a death drive.
TheMadFool August 04, 2017 at 03:50 #92889
Quoting Srap Tasmaner
the sort of syllogisms you're messing with have recently been featured in a TV show (an excellent TV show)


Sorry to bother you but can you give me a link, if there's one? Thanks.
Srap Tasmaner August 04, 2017 at 04:03 #92892
Reply to TheMadFool
A link to what?
TheMadFool August 04, 2017 at 04:24 #92896
Srap Tasmaner August 04, 2017 at 04:40 #92902
Reply to TheMadFool
Oh.
Orphan Black.
The syllogisms appear in a sort of test some people are given, but not until season 3.
TheMadFool August 04, 2017 at 11:13 #92946
unenlightened August 04, 2017 at 18:34 #93059
C. No suffering thing wants to suffer.

I can't be bothered to draw the diagram, but label your circles 'living things', 'things that suffer', 'things that want to suffer', and shade out what the premises tell you are empty regions.

Not the most exciting conclusion I've ever seen.
TheMadFool August 05, 2017 at 13:15 #93361
Reply to unenlightened thanks

Premise 1: All living things are things that suffer
Premise 2: No living things are things that want to suffer

Yes, the conclusion should be, as you said:


No suffering thing wants to suffer

But there's an error. The conclusion distributes the class ''things that suffer''.

However, it's not distributed (it should be) in the premises.

That's the problem. A more easier example is below (uses the same form):

All dogs are mammals
No dogs are cats
Conclusion???!!!

No cats are mammals???!!!
noAxioms August 05, 2017 at 13:26 #93369
Well, No mammals are cats, to follow the exact same form, but the two are the same statement.
So indeed, these are both examples of conclusions that don't follow from the premises.
unenlightened August 05, 2017 at 14:14 #93392
Reply to TheMadFool Oops, you're quite right, there can be non-living things that want to suffer and do.

Seems unlikely though! :D
TheMadFool August 05, 2017 at 16:13 #93401
Reply to unenlightened You don't see a problem?
charleton August 05, 2017 at 16:22 #93404
Reply to TheMadFool Both premises are false.
That being the case it is not worth persisting.
A tree is alive. A tree does not suffer. A tree does not want.

Even for living things that suffer, suffering implies not wanting. So the argument is circular and the venn diagram is not what you think it is.
TheMadFool August 05, 2017 at 16:25 #93406
Reply to charleton Ok.

What about this then:

Premise 1: All dogs are mammals
Premise 2: No dogs are cats
What is the conclusion?
charleton August 05, 2017 at 16:26 #93407
Reply to TheMadFool There is no conclusion here. The premises may be true but nothing further can be draw from them.
charleton August 05, 2017 at 16:27 #93408
Reply to TheMadFool Is you handle "Mad Fool" more than just a name?
TheMadFool August 05, 2017 at 16:29 #93410
Quoting charleton
There is no conclusion here. The premises may be true but nothing further can be draw from them


Why?
charleton August 05, 2017 at 16:32 #93412
Reply to TheMadFool Premise 1: All dogs are mammals
Premise 2: No dogs are cats

Because these are just two statements about dogs that are not connected.
unenlightened August 05, 2017 at 16:36 #93413
Reply to TheMadFool Quoting TheMadFool
You don't see a problem?


Only that I was wrong.
TheMadFool August 05, 2017 at 16:44 #93419
Delete
TheMadFool August 05, 2017 at 16:45 #93420
Quoting unenlightened
Only that I was wrong.


I can't see where the problem is.
charleton August 05, 2017 at 16:48 #93422
Reply to TheMadFool
[i]Argument A:
Premise 1: All dogs are mammals
Premise 2: No dogs are fish
We can draw a perfectly reasonable conclusion:[/i]
No fish are mammals
FALSE. No such conclusion may be made. Premise two only means a fish is not a dog. According to that premise a Fish could be the same as a cow or a pig.

You are either taking the piss. or are just stupid. Which is it?
TheMadFool August 05, 2017 at 16:50 #93425
Quoting charleton
Because these are just two statements about dogs that are not connected


I think you have a point. Can you be more specific
TheMadFool August 05, 2017 at 17:16 #93435
Reply to noAxioms Reply to unenlightened

I see something:

Argument A
1. All dogs are mammals
2. No dogs are cats
So,
3. Some mammals are not cats

Argument A is valid from the Aristotelean standpoint given that there's at least 1 dog.

However, from a Boolean perspective it's invalid. The Boolean perspective doesn't allow us to conclude anything from the premises. I wonder why.