Andrew Sullivan finds a putative Kerry malapropism in a letter from a reader:

My brother, Sean, debated Kerry back in 1970-71. Sean was a leader in Vietnam Veterans for a Just Peace. He and a colleague lunching with Kerry one time, before or after a debate, believe it or not.
Discussing some moral point or other, Kerry came out with: 'You just have to understand the higher modalities of the situation.'
This has been a catchphrase in our family ever since.

(The always-readable Tim Blair also picks up on it.)

Perhaps I'm misunderstanding the humor in the phrase, but I assumed that Kerry meant "deontic modalities" (i.e., rules of ethical behavior mandating that acts be obligatory, forbidden, or permissible). Although an idiosyncratic turn of phrase, it would certainly make sense if, for example, Kerry were defending a course of action against a consequentialist argument: "Regardless of the outcome of this act, I must do it because I am obligated to do it (or forbidden from doing it)." In other words, there's nothing particularly notable in Kerry's use of words, except that he was probably exposed to Kantian philosophy and probably never to modal logic at some point in his undergraduate career. (Sullivan, as an Oakeshottian, should well remember the many faces of modal logic, though I don't know Oakeshott's work well enough to know if he ever scrutinized deontology in so many words.)

Even if Kerry wasn't caught in a malapropism, there's still something amusing to me about his using a deontological argument in ethics, given the flip-flopping that seems to have been the hallmark of his political career. (Here's a modality for you: "It is forbidden to throw away another man's medals and claim them for your own.") But we'll leave that for another time.