Necessity cannot be derived from possibility because possibility is epistemic, not ontological.

Evidence

There is possibility when instead of being purely and simply what I am, I exist as the Right to be what I am. But this very right separates me from what I have the right to be. Property right appears only when someone contests my property, when already in some respect it is no longer mine. The tranquil enjoyment of what I possess is a pure and simple fact, not a right. Thus if possibility is to exist, human reality as itself must necessarily be something other than itself. This possible is that element of the For-itself which by nature escapes it qua For-itself. The possible is a new aspect of the nihilation of the In-itself in For-itself. — Jean-Paul Sartre, Being and Nothingness, 381 (#expands, via linked claim)

Certainty, necessity, impossibility; exhibited seriously in any other character than that of expressions of the degree of the persuasion entertained in relation to the subject in question, by him whose words they are, in the use of these words is virtually involved the assumption of omniscience. All things that are possible are within my knowledge, – this is not upon the list; such being interpreted is the phrase, this thing is impossible. — Jeremy Bentham, The Panopticon Writings, 615 (#complicates, via linked claim)

Categorization

• XREF: connects to: Leibnizian possibility is epistemic, relative only to our ignorance; Possibility is a concrete property of already existing beings, not a subjective construct — Jean-Paul Sartre, Being and Nothingness: An Essay on…, 378; Possibility exists only as an option on being that separates one from oneself — Jean-Paul Sartre, Being and Nothingness: An Essay on…, 381 (+3 more)

Broader Connections

• Possibility exists only as an option on being that separates one from oneself #expands (0.75) — Jean-Paul Sartre, Being and Nothingness, 381
• Using necessity or impossibility seriously covertly claims omniscience about all possibilities #complicates (0.72) — Jeremy Bentham, The Panopticon Writings, 615