14

Logic II 14

be quite impossible to draw a sharp line of demarcation
between two classes, although they are real and natural
classes in the strictest truth. Namely this will happen
when the form about which the individuals of one class
cluster is not so unlike the form about which individuals
of another class cluster but that variations from
each middling form may precisely agree. In such a
case, we may know in regard to any intermediate form
what proportion of the objects of the form belong had one
purpose and what proportion the other, but unless we
have some supplementary information we cannot tell
which ones had one purpose and which the other. The reader
may be disposed to suspect that this is merely a mathematician's
fancy, and that no such case would be likely ever
to occur. But he may be assured that such things occurrences are
far from being rare. I will mention one In order
to satisfy him that this state ot things does occur, I will