As the U.S. presidential race enters its 15th month, it is not unreasonable to expect that voters would, by now, have come to know each candidate intimately.

But despite the best efforts of opposition-research teams, countless debate moderators and enterprising reporters, they have not. For all the rhetoric, for all the anti-rhetoric, we still are in the dark as to how each contender would actually react to that 3 a.m. phone call.

And, to be sure, their reactions would look nothing alike. The notion, for example, that there is virtually no daylight between the policies and character traits of the two Democratic candidates is insupportable. Just consider how distinctively each Yale professor runs seminar discussions, conducts lectures or reacts to late assignments in order to understand how the most subtle personality quirks can determine leadership style — and, ultimately, success, mediocrity or failure. Now multiply that by 301 million for a true sense of scale.

Don’t, however, blame the candidates — or even the commentators. The fault is history’s alone: It is precedent, and not any deliberate attempt to muddy the waters, that creates this conundrum of campaigning.

The problem, in short, is that presidential styles have been as much determined by the secretaries, managers and strategists with whom presidnets have surrounded themselves as they have been by the personas and preferences of the leaders. Save for the micromanaging of the lot, commanders-in-chief over time have known well that they cannot run a country — or keep the free world free — all alone.

Our campaign system, however, does not reflect this basic maxim of leadership: Strangely, presidential candidates have rarely revealed their desired cabinets until after elections have been won. And all the tough questions, notwithstanding, they are rarely, if ever, pressured to do so.

This faulty model is the product of a far different era — the Founding — when the political inner circle was so relatively small that proposing a cabinet in advance would have been pointless. (During this era, after all, America even managed to persist for some time with a rule that the runner-up would become vice president.)

But in 2008, the time is ripe for this custom to change. The stakes are too high — and the substance of the campaigns too low recently — for candidates not provide the public with a (tentative, of course) cabinet now, not later. If Obama plans to name Sen. Chuck Hagel to his cabinet, as some have recently suggested, we should be aware of that before we press the lever; if Clinton thinks her secretary of state might be Sen. Joe Biden, we should be able to question him, too, on diplomacy; if McCain anticipates a bipartisan administration, Democrats and Republicans alike should ask, “Who?”

The slates need not be precise, and the individuals named need not accept the role, but the outcome would be powerful: A real glimpse, at last, into the candidates’ abilities to identify talent and principled leadership in others as well as into their likely approaches to the great burdens — from defense and diplomacy to education and urban development — they will inevitably face. The solution may seem imperfect, but far more unsatisfactory, we think, is the status quo.

It is an inconvenient irony that a leader is best evaluated by using others as a prism. But the greater — and far more tragic — irony is that a race so longwinded could be so shortsighted.