The negative form of can1
The idiomatic phrase cannot but
has sometimes been criticized as a double negative, perhaps because it has been confused with can but.
of cannot but,
however, means “except,” as it does in phrases such as no one but,
while the but
of can but
has the sense only,
as it does in the sentence We had but a single bullet left.
Both cannot but
and can but
are established as standard expressions. • The construction cannot help
is used with a present participle to roughly the same effect as a verb form ending in -ing
in a sentence such as We cannot help admiring his courage.
This construction usually implies that a person is unable to affect an outcome normally under his or her control. Thus, saying We could not help laughing at such a remark
would imply that one could not suppress one's laughter. • The construction cannot help but
probably arose as a blend of cannot help
and cannot but;
it has the meaning of the first and the syntax of the second: We cannot help but admire his courage.
The construction has sometimes been criticized as a redundancy, but it has been around for more than a century and appears in the writing of many distinguished authors. • The expression cannot
) seem to
has occasionally been criticized as illogical, and so it is. Brian can't seem to get angry
does not mean “Brian is incapable of appearing to get angry,” as its syntax would seem to dictate; rather, it means “Brian appears to be unable to get angry.” But the idiom serves a useful purpose, since the syntax of English does not allow a logical equivalent like Brian seems to cannot get angry;
and the cannot seem to
construction is so widely used that it would be pedantic to object to it. See Usage Notes at but