Claiming all A cannot be B in one set because all A are not B in every set

Hi, Mr. william!

         Trying my best to wade through your example, it seems to me that your interlocutor was not stating that all the birds in Anytown are silly , just the geese in Anytown are silly . These are two different statements, which is proven by the fact that it is logically possible both that the first statement is false and the second statement true.

         You say that your interlocutor was calling all birds in Anytown silly. Whether you are right or wrong depends on what exactly you are trying to say. If you are saying that he stated that everything in Anytown is such that if it is a bird, then it is silly , you are wrong. What he stated, from what I see, is that every goose, not every bird, in Anytown is silly. Again, those really are different statements, as I explained in the paragraph above. If you are merely saying that because all of the birds in Anytown are geese, the set of silly geese and the set of birds perfectly overlap, then you are right in saying that he "called" all the birds in Anytown silly. Though, you would have to acknowledge that there is a difference between calling all the birds silly and stating that all the birds are silly. For even if the set of birds and geese happen to overlap in Anytown, your interlocutor was still making a statement only about geese, not birds per se .

Thank you, Mr. william.

From, Kaiden

It’s difficult to follow your example the way you worded it, but if you have the statements:

1.  There are some sets where all A are not B

2. Therefore, in set S, all A are not B   

Although this is not a syllogism (which has 2 premises and a conclusion), this is basically the Undistributed Middle fallacy.   1 is only talking about some sets; it isn’t making a statement about all sets.    Therefore you can’t conclude anything about all sets.  

A counterexample would be: 

there are some restaurants where all sandwiches are not hamburgers   
Therefore, in the Hamburger Shack, all sandwiches are not hamburgers.  

The conclusion doesn’t follow