Suppose we know that (1) Some Yob is not a Slob, and (2) No Slob is a Blob.
If “some” means “at least one”, then we can conclude which of these?
Some Yobs are not Blobs.
Some Blobs are not Yobs.
No Yob is a Blob.
Some Yobs are Blobs.
None of the above.
Solution
A Venn diagram of this situation is below. We cannot tell whether the three regions marked with a question mark are empty or not. The problem is that while there must be a Yob who is not a Slob (this is assumption 1), this particular Yob might or might not be a Blob. Therefore, we can’t deduce (a), (b), (c), or (d). The correct answer is (e).
