Television's favoured tactic is to send the presenter on a "journey" - to use the current jargon. Professor Schama is one of our great historians. No one who has read him can doubt his ability to investigate and explain. However, instead of allowing him to tell us what he knows, the BBC instructs him to travel across the US and tell us what he feels.

Voyages of emotional discovery produce solipsistic journalism at the best of times. They work crashingly badly in American Future because the series is arranged thematically. In separate episodes, Professor Schama looks at the environment, religion and war. The narrative has to begin afresh each week, and the BBC should have accepted that the form it had chosen obliged it to allow him to explain his argument at length every time he began a new story. But giving the professor his head would have risked producing "boring" TV. Too many lectures and not enough scene changes. Instead of letting him elucidate, the BBC instructs him to go short on evidence and long on play acting.

The programme on the American way of war illustrates the perils of anti-intellectualism. Schama believes that America has been torn since its foundation between the principles of Thomas Jefferson, who wanted American soldiers to be citizens in uniform, and the realpolitik of Alexander Hamilton, who wanted the American army to behave like the armies of any other great power. I have my disagreements with his Manichean view - after all, as President, Jefferson organised an imperial land-grab with the Louisiana Purchase, and fought his own war on terror against the Barbary pirates. The trouble with this programme, however, is not whether its argument is right or wrong, but that the BBC gives Schama so little time to make it before packing the poor man off on another trip.

It takes him to the battlefield of Gettysburg. I think Schama wanted to argue that the Union forces began the conflict as good Jeffersonians but had to resort to brutal Hamiltonian measures to win. I say "I think" because instead of explaining himself, he gushes with all the lachrymose fervour of the late Princess of Wales.