Usage Note: The choice of what conjunction to use following
doubt and
doubtful is a perennial usage problem. When
doubt and
doubtful indicate strong uncertainty, the Usage Panel prefers
whether and
that over
if. In our 2008 survey, 51 percent indicated that they would use
that, while 43 percent preferred
whether in the following sentence:
At one time it was doubtful [that/whether/if] the company could recover from its financial difficulties, but the government loan seems to have helped. Only 6 percent said they would favor
if in this sentence, probably because
if has a more informal tone. When the expectation for the outcome is negative,
that tends to be used. Some 86 percent of the Panel prefer
that in the sentence
I doubt [that/whether/if] it will rain tomorrow (where the expectation is that it probably won't rain), with
whether getting the preference of only 6 percent and
if getting 7 percent. Note that, in certain kinds of sentences, the choice of conjunction can carry subtle differences in implication.
That is the best choice when the truth of the clause following
doubt is assumed, as in negative sentences and questions. Thus
I never doubted for a minute that I would be rescued implies "I was certain that I would be rescued." By the same token,
Do you doubt that you will be paid? may be understood as a rhetorical question meaning "Surely you believe that you will be paid," whereas
Do you doubt whether you will be paid? expresses a genuine request for information (and might be followed by
Because if you do, you should make the client post a bond). Note that it is also acceptable to omit
that in these sentences:
I doubt she will accept the nomination. In other cases, however, this distinction between
whether and
that is not always observed. · When
doubt is negated to indicate belief or certainty, the clause following
doubt is sometimes introduced with
but that or simply
but, as in
I do not doubt but that they will come. This construction has been used by many fine writers, but some critics object to its use in formal writing. Dropping the
but easily solves this problem. See Usage Notes at
but,
if.