Philosophy Now Forum

Given that all birds are animals,
And some animals are pets
It follows that, some birds are definitely pets


Is this argument valid invalid??

amber1331 wrote: ↑Mon Feb 12, 2018 8:16 pm Given that all birds are animals,
And some animals are pets
It follows that, some birds are definitely pets


Is this argument valid invalid??

It is not entirely valid considering some animals, does not equate to all birds. While all birds may be animals, not all animals are birds.

"Birds" and "Animals" are fundamentally sets of information.

"Bird" may be part of the information set of "animal" but the set of animal may contain a greater degree of information than the set of bird.

So while the bird as "X" may exist as the animal in set "A", Set A = {X,Y,Z,1,2,3}. The argument further states as "some" being a fraction of the set of A. A fraction of the set does not equate to all variable in the set being divided, but rather just the set itself. Set A may be divided as

____{X,Y,Z,1,2,3}____ ≠ ___X___ ___Y___ ___Z___ ___1___ ___2___ ___3___
............S......................S..........S..........S..........S.........S.........S


While a bird may be one set of animals, and some sets of animals are pets, not all sets of animals are all pets.


In my opinion is a logical argument of implication not definition. If the conclusion was worded as follows "It follows that some birds may be pets" then I would argue it is correct.

The part of the question which will confuse people is the fact that they observe empirically that birds exist as pets, however the logic of the argument does not give a degree of definition equating to birds as pets. It's definition only observes logical possibility, by acknowledging it as a set of potential variables, whether they are actual or not is a separate issue.

It's invalid. Just draw a large box on a piece of paper, and label the box animals. Then, draw a circle and that circle inside the box cann represent birds. This shows that all birds are animals. Now, draw another circle, that does not intersect with the circle for birds, and label that circle pets. Thus, you can see that it can be true that all birds are animals and all pets are animals without any bird having to necessarily be a pet.

Science Fan wrote: ↑Fri Feb 23, 2018 5:47 pm It's invalid. Just draw a large box on a piece of paper, and label the box animals. Then, draw a circle and that circle inside the box cann represent birds. This shows that all birds are animals. Now, draw another circle, that does not intersect with the circle for birds, and label that circle pets. Thus, you can see that it can be true that all birds are animals and all pets are animals without any bird having to necessarily be a pet.

Those Venn diagrams will do it every time.

PhilX

amber1331 wrote: ↑Mon Feb 12, 2018 8:16 pm Given that all birds are animals,
And some animals are pets
It follows that, some birds are definitely pets


Is this argument valid invalid??

Invalid, as "some birds" are not necessarily included in the group "some animals."

amber1331 wrote: ↑Mon Feb 12, 2018 8:16 pm Given that all birds are animals,
And some animals are pets
It follows that, some birds are definitely pets


Is this argument valid invalid??

You know ... if you're studying elementary logic and you have this question ... I would like to know, what do YOU think?

The reason I ask is that the answer is much less important than how you go about getting it; and in particular, how you learn to go about getting it. This problem is one that you can think through from common sense and everyday experience.

wtf wrote: ↑Sat Feb 24, 2018 4:26 am

amber1331 wrote: ↑Mon Feb 12, 2018 8:16 pm Given that all birds are animals,
And some animals are pets
It follows that, some birds are definitely pets


Is this argument valid invalid??

You know ... if you're studying elementary logic and you have this question ... I would like to know, what do YOU think?

The reason I ask is that the answer is much less important than how you go about getting it. This problem is one that you can think through from common sense and everyday experience.

Second that point, I also want to know what the teacher says is the right answer.