In the introduction to Process and Reality, Whitehead criticizes the tendency to posit logical or ontological necessity as the primary modes of cosmological explanation. For Whitehead time is a contingent specification of extension. Extension is not synonymous with space, but stems from a higher level of generality as the “undivided divisibile” or “extensive continuum.” Employing a functional definition Whitehead argues we are only in a position to say that time and space should not be treated as necessary modalities despite lacking experience with any non-temporal mode of division beyond our cosmic epoch. However, the limits of experience are not exhaustive of the limits of imagination!
Knowledge is derived by contrast and the lack of contrast implies the absence of knowledge. When categorizing our experience of time and space as modes of possible divisions of the extensive continuum (receptacle of the universe), Whitehead argues we have no grounds for claiming anything more than that temporal and spatial relations are contingent. They are the modes of division in our immediate epoch--i.e. not the whole cosmic epoch, which impose conditions on the metaphysical description of the present.
As Randall Auxier and Gary Herstein argue in their forthcoming book The Quantum of Explanation, which is an intense study of Whitehead’s robust philosophy, “The absence from our experience of other equally primary modes of dividing the extensive continuum is not evidence for the necessity of time and space as its dividers (that is, ultimately, actual entities), it is rather the best reason to treat them as contingent, and to hold open the possibility of other (as yet unknown) modalities of division. Hence, we find Whitehead carefully offering conjectures about what might hold of other cosmic epochs. This process of entering conjectures is familiar to mathematicians, and it does carry with it a kind of weight of expectation, but its principal function is to remind us that the present inquiry exists in a context wider than we can expect to encompass with our hypotheses.”
The insistence upon necessity prevalent in popular science is the kind of dogmatism Whitehead insists philosophers, especially scientists, should resist. Most of the history of science and philosophy has assumed we should without questioning it accept the overstatement. But if the order of nature can change within our cosmic epoch (e.g. laws of nature evolve) then what grounds do we have for adopting the reductionist thinking which says that the conditions of our immediate order holds for all orders?