Here is an odd feature of the verb to cause. When Jen is lighting the fuse, we say:
(1) "Jen's lighting the fuse will cause the firework to go off."
When the firework is going off, we say:
(2) "Jen's having lit the fuse caused the firework to go off (or to be going off)."
So, we would expect that there should be some time in between the lighting of the fuse and the firework's going off when we should say:
(3) "Jen's having lit the fuse is now causing the firework to go off."
When would we say (3)? It's kind of odd, isn't it? The problem is that it seems to me we can't say (3) while the firework is going off, for then (2) is appropriate, and before the firework goes off, the appropriate thing to say is (1) or perhaps:
(4) "Jen's having lit the fuse will cause the firework to go off."
The one time I can think of where (3) is appropriate is at the time of the transition between the firework's not going off and the firework's going off; that seems to be "when the causation is happening". But for (3) to be appropriate, it has to be the case that at the transition point the firework is not actually going off. So (3) will never be appropriate if the firework goes off exactly at noon, and at no time prior to noon was it going off. For then the only transition point is noon, but at noon it is (2) that is appropriate, not (3).
Does any of this matter, except as a curiosity about the verb to cause? Perhaps the verb just has this odd feature that its future tense tracks the time of the object and its past tense tracks the time of the subject and we have a convention as to how we switch between these two? And don't we expect grammatical oddity in regard to a verb that spans times?
Maybe. But those philosophers of time who think that our language's tense matters very much, and who therefore think that the present is somehow objectively very different from the past, should also take the tense of to cause seriously. For the fact expressed by this verb in cases where there is temporal distance between cause and effect appears never to be a present fact. And that puts into question the idea of the present as ontologically primary.