Posterior Analytics   

predication. If no term in the series ACD...is predicable of any
term in the series BEF...,and if G-a term in the former series-is
the genus of A, clearly G will not be the genus of B; since, if it
were, the series would not be mutually exclusive. So also if B has a
genus, it will not be the genus of A. If, on the other hand, neither A
nor B has a genus and A does not inhere in B, this disconnexion must
be atomic. If there be a middle term, one or other of them is bound to
have a genus, for the syllogism will be either in the first or the
second figure. If it is in the first, B will have a genus-for the
premiss containing it must be affirmative: if in the second, either
A or B indifferently, since syllogism is possible if either is
contained in a negative premiss, but not if both premisses are
negative.
Hence it is clear that one thing may be atomically disconnected from
another, and we have stated when and how this is possible.

16

Ignorance-defined not as the negation of knowledge but as a positive
state of mind-is error produced by inference.
(1) Let us first consider propositions asserting a predicate's
immediate connexion with or disconnexion from a subject. Here, it is
true, positive error may befall one in alternative ways; for it may
arise where one directly believes a connexion or disconnexion as
well as where one's belief is acquired by inference. The error,
however, that consists in a direct belief is without complication; but
the error resulting from inference-which here concerns us-takes many
forms. Thus, let A be atomically disconnected from all B: then the
conclusion inferred through a middle term C, that all B is A, will
be a case of error produced by syllogism. Now, two cases are possible.
Either (a) both premisses, or (b) one premiss only, may be false.
(a) If neither A is an attribute of any C nor C of any B, whereas
the contrary was posited in both cases, both premisses will be
false. (C may quite well be so related to A and B that C is neither
subordinate to A nor a universal attribute of B: for B, since A was
said to be primarily disconnected from B, cannot have a genus, and A
need not necessarily be a universal attribute of all things.
Consequently both premisses may be false.) On the other hand, (b)
one of the premisses may be true, though not either indifferently
but only the major A-C since, B having no genus, the premiss C-B
will always be false, while A-C may be true. This is the case if,
for example, A is related atomically to both C and B; because when the
same term is related atomically to more terms than one, neither of
those terms will belong to the other. It is, of course, equally the
case if A-C is not atomic.
Error of attribution, then, occurs through these causes and in
this form only-for we found that no syllogism of universal attribution
was possible in any figure but the first. On the other hand, an
error of non-attribution may occur either in the first or in the
second figure. Let us therefore first explain the various forms it
takes in the first figure and the character of the premisses in each
case.
(c) It may occur when both premisses are false; e.g. supposing A
atomically connected with both C and B, if it be then assumed that
no C is and all B is C, both premisses are false.
(d) It is also possible when one is false. This may be either
premiss indifferently. A-C may be true, C-B false-A-C true because A
is not an attribute of all things, C-B false because C, which never
has the attribute A, cannot be an attribute of B; for if C-B were
true, the premiss A-C would no longer be true, and besides if both
premisses were true, the conclusion would be true. Or again, C-B may
be true and A-C false; e.g. if both C and A contain B as genera, one
of them must be subordinate to the other, so that if the premiss takes
the form No C is A, it will be false. This makes it clear that whether