# The probability that it "be" or "is" -- subjunctive?

I am writing a scientific paper, and would like my diction to be as precise as possible. Regarding the subjunctive mood, I know the following is correct:

"It is important that she be at home by 9 p.m.".

However:

"The probability that temperature exceeds its historical maximum is large."

sounds to me better than

"The probability that temperature exceed its historical maximum is large."

Which one is correct? Is it a matter of taste?

• Only "exceeds" is OK here. Apr 27, 2021 at 13:50
• No - not every use of "that" needs the subjunctive (most don't). You could say "The probability of the temperature exceeding ..." which might be better depending on context (and would probably work well in situations where other languages might use a subjunctive). Apr 27, 2021 at 13:57
• Pick a card. What is the chance that it be an ace? A few writers (mostly over a century ago) have used "subjunctive" be there, but the vast majority of us stick to Simple Present / Future (...that it is / will be an ace). So I'd say it's "a matter of taste" - but if you're not a native speaker stick with the majority. Apr 27, 2021 at 14:24
• The noun "probability" does not license a subjunctive clause as complement, so only your first example is correct. Apr 27, 2021 at 14:47
• The subjunctive is generally used as a form of 'mandative' construction. A mandative construction tells the listener about some outcome which is considered desirable. These types of clause are complements of verbs such as "suggest/rule/order/insist/demand" or nouns such as "requirement/demand/recommendation" or adjectives such as "mandatory/imperative/ important". The reason the subjunctive is ok in example (1) is because "important" introduces an idea of a desired result. In contrast "probability" does not. It is entirely neutral about the outcome. A subjunctive is not possible here. Apr 27, 2021 at 17:35