Peguins are black and white.Some old TV shows are black and white.What can you properly infer?

Skylar September 28, 2019

Happy to help. Let's take a look.

The first sentence states "Penguins are black and white." This can be diagrammed as: P->BW and the contrapositive is: not BW -> not P. We know that we can also change S->N statements to N-some-S assuming S exists. Following this, we have: BW-some-P.

The second sentence states "Some old TV shows are black and white." This is diagrammed as: old TV shows - some - BW. It can also be rearranged to: BW - some - old TV shows.

So, we have:

P -> BW
not BW -> not P
BW - some - P

old TV shows - some - BW
BW - some - old TV shows

In order to make a valid deduction, we know that we must meet two requirements:

(1) We must have a S->N statement (except in the case of two most statements with a common left side.) Since we have P ->BW, this condition is met.

(2) We must have the Sufficient condition in common. The Sufficient condition in this case can only be (P) or (not BW), as these are the only two conditions that occur before the arrow in our breakdown of the first sentence. Since this condition is not met, we cannot properly infer anything and the correct answer is (E) "no valid conclusion."

Your suggestion of "some old TV shows are not penguins" due to "the lack of a shared attribute" is incorrect, because the lack of information on that relationship indicates that we do not necessarily know its connection. It does NOT indicate that we know there is no connection at all. In questions like these, we should only look to what we can directly support from the given text.

Does this make sense? Please let us know if you have any other questions!