Revisionism.

Henry Ford said that history is bunk. Someone else--who?--claimed that history is a fable agreed upon. But not everyone agrees. Fernand Braudel once said that the way for the young to make a reputation is to take an agreed fable and to revise it. Examples abound:

A new book by Peter Garber says that the Tulipmania, the Mississippi, and South Sea bubbles were not bubbles but can be explained by "fundamentals."

Daniel Goldhagen denies the Holocaust in Nazi Germany.

Alan Milward claims that there was no necessity for the Marshall Plan; Europe was recovering normally. And Charles Maier believed that there was no serious danger that Italy or France would become Communist.

Rondo Cameron has held that there was no industrial revolution in Britain.

Patrick O'Brien and Caglar Keyder have written that France was as rich as Great Britain in the late Eighteenth Century before the revolution.

It is important to distinguish disagreement from revisionism. Historians disagree on causes of such an event as the French Revolution, emphasizing unrest in the cities, bad harvests in agriculture, taxation, and especially the gabelle, the heavy tax on salt. Pouring over archives, they tend to choose an outstanding cause for parsimony, rather than the complex tangle that often existed. Contrary evidence may be ignored--the jump in British patents after 1766; or dismissed--the account of Arthur Young's travels through France before the Revolution, commenting on the poor condition of French agriculture compared to that of the British. At a personal level, I confess to not having read the Goldhagen book, but feel no need to do so having visited the concentration camp at Nordhausen in April 1945, and having seen conditions with my own eyes.

Whether the Marshall Plan was called for or not introduces another question: insurance versus risk. After the fact, it may be appropriate to introduce what economic historians call a "counter-factual," what would have happened if the action had not been taken? There is no way to be sure, of course, but one can make a judgment and defend it. At the time, however, any forecast is uncertain, and a risk-averse person or country may well want to take out insurance. More daring people will not, and choose, with a small number of economists in 1947, and Senator Joseph Ball, to think it safe enough to get European countries to balance their budgets, fix their money supplies, and depreciate the currency to the purchasing-power parity.

Whether speculative bubbles sometimes go too far and implode, as bubbles do, or are simply reactions of efficient markets to fundamentals (albeit in some cases, to governments changing the rules), seems to me to rest on one's view of the evidence to some extent, but also on prior beliefs. These are chosen from a wide spectrum: Markets are always efficient; markets are mostly dominated by monopolies, speculative excess, or governmental mistakes, or, a more complex view, both--in variable proportions.

Age may count, as well as path dependency. The young are more ready to revise than their seniors, especially, perhaps, the elderly. And a notion, strongly embraced in youth, may be clung to tenaciously. As Walter Pagehot said of Malthus, "No man who once had an original idea ever gets rid of it." My reaction to revisionism is not original, but taken from a physicist colleague many years ago: "Everything is more complicated than most people think."

Charles P. Kindleberger is Professor Emeritas at MIT.