The phrase "alternate possibility" is correct and usable in written English.
It can be used when discussing different options or scenarios that could occur instead of the one currently being considered.
Example: "If the current plan fails, we need to explore an alternate possibility to ensure the project's success."
Alternatives: "alternative option" or "different possibility".
We'll probably travel to India and Bangladesh, although Congo is an alternate possibility.
But I'm going to suggest an alternate possibility: Trump's cause is also harmed by trivial, petty and burlesque distractions.
An alternate possibility is that a larger silencing complex of some sort8 interacts with Clr4 (ref. 10).
An alternate possibility is that NSCs generate new oligodendrocytes at a level that is low under 'baseline' conditions but higher in response to stress.
But from the beginning, F.B.I. agents have kept open an alternate possibility -- that the attack may have involved powerful figures inside Yemen with close ties to Osama bin Laden, the F.B.I's most-wanted terrorist.
The old adage holds that those who fail to learn from history are doomed to repeat it, but the candidacy of Donald Trump suggests an alternate possibility — that sometimes we repeat history precisely because we understood it the first time.
Harry Frankfurt, "Alternate possibilities and moral responsibility" 16.
But there have been subtle hints that alternate possibilities are not being rejected out of hand.
Biography obviously doesn't replace close reading, but it provides alternate possibilities, new, otherwise inconceivable modes of appreciation.
She saw alternate possibilities, like installing the deep fryer and lining up its permits in stages, after the store reopened.
In an influential paper, "Alternate Possibilities and Moral Responsibility" (1969), the American philosopher Harry Frankfurt questioned whether the ability to do otherwise is truly necessary for freedom.
