Despite what the finger-pointing politicians have been declaring with more heat than enlightenment, there was no single identifiable cause for the stock markets' collapse. But one significant factor has been overlooked: the absence of Paul Volcker's steady hand at the helm of the Federal Reserve Board.

Investors finally learned what a few government and financial insiders have known for months: Volcker was forced out by Treasury Secretary James Baker. That, more than his much-criticized jawboning in West Germany, is the most serious responsibility Baker must bear in the market debacle.

For eight years, Volcker had been the second most powerful man in Washington, controlling the nation's money supply, deciding practically single-handedly whether interest rates would rise or fall and whether the economy would boom or bust. Though he was on an irreversible collision course with the White House and President Reagan's appointees on the Federal Reserve Board, Volcker told intimates he was willing to stick it out for a while from a sense of duty, and a fear that after him would come the deluge.

But then Volcker realized that Baker had the long knife out for him. As Volcker described the furtive undercutting to friends, Baker's loyal undersecretary, George Gould, orchestrated a campaign of anti-Volcker leaks. Too proud to fight this kind of guerrilla war, Volcker quit.

Volcker didn't say any of this publicly. He knew the impact his every utterance could have in Wall Street, so he was always careful to share his concerns with only a few trusted friends, our associate Michael Binstein was told.

Our sources say Volcker is afraid the whole economy is tottering on the brink -- and he feels the White House is to blame. Like a handful of shrewd investors, he knew there would have to be a day of reckoning for Wall Street's speculative binge and unbridled borrowing. He is depressed over the corruption in Wall Street -- and the permissive mentality in Washington that encouraged it.

Before the sobering experience of the market crash, Volcker privately expressed misgivings that have since become conventional wisdom: politicians are mortgaging the country's future by putting off the tough but necessary decisions on the deficits, just as consumers are sinking ever deeper in debt, happy with the tax cuts and heedless of the awful legacy they will be leaving to their children and grandchildren.

Can Alan Greenspan fill Volcker's size 13s at the Fed? Probably not, but few could.

Greenspan shares Volcker's healthy fear of inflation. But Greenspan favors deregulating the entire financial system. In Volcker's eyes, this is a prescription for disaster.

A consummate political operator, Greenspan has aroused concern in some circles that he will be too attentive to the desires of conservative Republicans. Actually, the word we get is that the GOP right still distrusts him for encouraging an anti-inflation hike in interest rates when he chaired President Ford's Council of Economic Advisers. The resulting recession, the conservatives are convinced, gave Jimmy Carter the edge he needed to win in 1976.

Like Volcker, Greenspan will have to contend with a Federal Reserve Board that loves tax cuts and easier money. If the chairman resists these Dr. Feelgood policies, he could cut away his own GOP power base.

Greenspan is also believed to agree that some kind of tax increase will be necessary to attack the deficit, and he favors loosening the regulatory reins on the banks. Both of these views are shared by Treasury Secretary Baker -- though in the aftermath of the market collapse, Congress is unlikely to allow further deregulation that would put banks into real estate, insurance, financial brokerage and other fields.

It was deregulation, in fact, that set Volcker and Baker at each other's throats. Volcker was alarmed at the blurring that has already taken place between financial and nonfinancial firms, and kept warning that the megabanks and financial-service conglomerates would soon be beyond effective control of federal agencies. In the new, more cautious, post-crash environment, these warnings seem sure to be taken to heart, on Capitol Hill if not in the White House.