What are historians doing when they explain things?

I've been thinking more about explanation & causation in history recently. It seems to me that there are structural elements in both film and narrative that are quite similar to the Humean model of causation: that is to say, images or phrases are placed one after the other, and the viewer or reader has a"habit-driven" inclination to infer the (causal) relationship between the two. Examples:

From film: (1) A camera shot shows one person pointing a gun; (2) the camera cuts to another man falling to the ground, accompanied by a gunshot. Post hoc, ergo propter hoc. (2) happened because of (1).

Or in fiction, we might have this passage:

(3) She refused to go to work today. (4) Her head throbbed with almost military vigour.

Reading the two in succession, we tend to assume a causal relationship, even in the absence of any explicit"because". (Post hoc, ergo propter hoc). By the end of it, the second sentence has become an explanation of the first, Interestingly, in this case we do assume causation, whereas in the following case, we would probably, unless context demanded it, not:

She refused to go to work today. Her cat ate some cheese.

The causal relationships are inferred by us; there is no need for an explicit"because". (Furthermore, inserting an explicit"because" between (3) and (4) seems to injure something stylistic about the passage. And is history-writing not, after all, in part a stylistic enterprise?) Narrative in general seems to be a series of individual statements about what-is-the-case, which, taken collectively, may be joined up by habit-driven inference on the reader's part, as above. In historical narrative, then, it seems to me that a series of individual statements about e.g. what happened in the years leading up to 1939 can become, by the last sentence, an explanation of it. And so, the common distinction between a chronicle and a history -- that the latter explains while the former does not -- isn't quite so clear cut, if it seems possible that a chronological series of well-selected statements can, in fact, yield an explanation by the end of it. Which is, I think, the entire value of narrative history.

'Well-selected' here is the key, of course. My dear, long-suffering boyfriend Adam, who puts up heroically with my torturous ruminations (and indeed subjects me to his own), wrote me the following to make the point that an unselective chronicle might, in fact, look nothing like a narrative:

Events of the year X:
The commencement of King Cuthbert the Flatulent's reign. (A)
A rain of frogs in Wessex.
A monkey is hanged as a presumed foreign combatant by a group of Yorkshire villagers.
Pope Pius XXXVII is defenestrated. (B)

Events of the year X+1:
The weeping visage of the Virgin Mary appears in the sky as Carcasonne falls to the Cathars.
It is revealed that Pope Pius XXXVIII is a woman. (C)

Events of the year X+2:
King Cuthbert spontaneously combusts during a battle with King Canute of Denmark. (D)
Lisbon is engulfed by a tidal wave. (E)
The population of Rome is decimated by a terrible pestilence. (F)

Events of the year X+3:
Pope Pius XXXIX is appointed. (G)
Yellow devils on horseback descend on Poland and Hungary, burning Pest and Lvov.
A rain of communist pamphlets falls on Paris. (H)

Events of the year X+4:
The Irish potato crop fails. (I)
Barricades appear on the streets of the French capital. (J)

Events of the year X+5:
Parliament passes legislation permitting Irishmen to eat their babies. (K)
Dostoevsky publishes Crime and Punishment.

Further points about our habits of causal inference, Adam adds:"There are several items in this chronicle that are difficult for us not to link causally: (A) and (D), for instance, or (H) and (J). Why? We perhaps associate (for no very good reason) flatulence (A) with spontaneous combustion (D); we have grounds to suppose that a city's first exposure to communist ideas (H) could lead to a workers' uprising and thus to barricades (J). Many people in the past would have been tempted to infer a causal relationship between (C), (E) and (F). We know better."

And though we might infer an unhappy causal relationship between (I) and (K), the inclusion of those two statements, related or not, seem to cast doubt on the veracity of the whole document. And rightly so, it being a Chronicle of Unfettered Though Amusing Fabrication. But that we have in the past inferred such causal relationship between events that we now know better not to (C, E and F) is a little worrisome: it's where, for example, the issue of standards of justification come into play in history, and it's why I think it's important to wonder now and then: what are historians really doing when they explain things?