As far as necessity goes, forms of necessity are essentially defined with reference to all possible examples of some kind. A temporal necessity is true for all possible times; a physical necessity is true for all possible physical dynamics (or: for types of causation, a physical necessity is true of all possible tokens per type); a logical necessity is true for all possible logical systems—and so when logic is self-applied while standing both above and within all other kinds of systems, we end up with a picture of logical necessity as the most absolute necessity there could be.
Now, one might deny that there is such a necessity in the first place, although if this were so, then it would seem to be necessary that nothing was necessary: for if it were logically possible for something to be logically necessary, then in the end it would seem as though the mere possibility of something's absolute necessity would mean the actual necessity of that thing. As Kant put it: to say that something is necessary is to say that it is actual just by being possible; or in contemporary modal logic, "possibly necessary" collapses to "necessary."
However, one famous thinker who sought to imagine that eternal truths could be contingent was Descartes:
Another reason that Descartes’ view is difficult to conceive is that Descartes takes eternal truths to be necessary. That is, it is difficult to conceive how eternal truths could be necessary if they were created by a free act of God. Descartes is clear that the eternal truths are necessary: he says that “the necessity of these truths does not surpass our knowledge” (“To Mersenne, 6 May 1630,” AT 1:150, CSMK 25). If eternal truths are necessary, however, it should not be the case that they could have been otherwise. Yet Descartes’ commitment to divine omnipotence appears to commit him to this view...
So it is that some analysts don't accept that iterated modalities always collapse to whichever directly prefixes the modified terms. With respect to Descartes' viewpoint, they say:
An alternative view (developed and defended by Edwin Curley) is that Descartes holds that eternal truths are necessary, but that they are not necessarily so. On this reading, Descartes’ view involves iterated modalities: a number of truths are possibly necessary, but God chooses only some of these possibilities to be the actual necessary truths.
For a broader, recent discourse on iterated modalities, see Gregory.