Why Does "Believe" Have No Present Progressive?

In English, the distinction between dispositional and occurrent uses of verbs is often marked in the present tense, dispositional uses taking the simple present and occurrent uses taking the present progressive. For example: "Corina runs" usually suggests that Corina has the tendency, or disposition, to run, though she may not be running now; while "Corina is running" suggests that running is going on at the very moment of the utterance. "Jamie reads the Bible" suggests that Jamie has the habit of reading the Bible from time to time; while "Jamie is reading the Bible" suggests that Jamie is presently (whether in a narrow or broad sense of the present) reading some bit of, or in the course of reading through, the Bible.

Most philosophers of mind accept a distinction between dispositional vs. occurrent senses of belief as well. Five minutes ago, before the thought crossed your mind, you dispositionally believed that Jupiter is a planet. Now that you're thinking about it, you occurrently believe that fact. The idea is that we can talk about a person's beliefs dispositionally, without knowing what is presently running through her mind (she might even be in a dreamless sleep), but that beliefs also sometimes come up front, as it were, to play a role in active inference or conscious reasoning, in some more occurrent sense.

It's interesting, then, that ordinary English usage has no (or at least very little) use for the present progressive form of "believes", which we might think would be the natural way to talk about occurrent belief as it occurs. We don't say "Harry is believing that New York City is large." Indeed, my version of MS Word marks that sentence as ungrammatical -- though it has no problem with "Harry is saying that New York City is large"! Likewise, if you search for "is believing" in Google, you find instance after instance of "seeing is believing". If you exclude pages with "seeing", you'll find "hearing is believing", "stealing is believing", and the like, but not a present progressive in sight!

Philosophers of mind sometimes point out that in ordinary English we often use "thinks" to ascribe beliefs: "Joan thinks plaid ties are chic". But here again, English steers us away from occurrent belief: The present progressive of "thinks" -- "is thinking" -- generally does not ascribe an occurrent belief: "I am thinking of Paris", "Jee Loo is thinking about philosophy". Perhaps closest to an ascription of occurrent belief, with the present progressive "is thinking" in natural English, would be something like this: "I've been thinking that maybe we should be leaving soon". But even that last seems not so much to ascribe the belief that maybe we should be leaving soon as the thought that we should be.

I'm not a huge fan of the examination of ordinary language to reveal truths about the mind -- at least in the way philosophers have often done it. But in this case, I wonder if English usage isn't onto something. I wonder whether, maybe, there's enough of a difference between occurrent mental states, like thoughts and judgments, and dispositional ones like beliefs, that we shouldn't simply assimilate the former into the latter in the guise of "occurrent belief".

(If so, this would fit nicely with my sense -- as explored in my earlier racism and God & Heaven posts -- that we often sincerely judge or assert things we don't fully and genuinely believe.)