There is a certain kind of cynicism that is more naive in its way than the most credulous naif could ever manage. To believe that nothing is as it seems, that everything is a lie, is as foolish as the belief that ''everything is for the best in the best of all possible worlds.''

This sort of they-faked-the-moon-landing cynicism is the basis for the enduring public conviction that the only reason the U.S. and other countries have sent troops to the Persian Gulf is to secure a steady supply of cheap oil. President George Bush can scarcely step out the door without facing a group of protesters bearing a ''No Blood for Oil'' sign, nor open the paper without finding a homily on how this is all for lack of an ''energy policy.''

FIRST IMPRESSIONS

Bush brought this on himself to a large extent. Floundering about in search of a justification for a military response to Iraq's invasion of Kuwait, Bush argued ''our way of life'' was at stake, perhaps thinking this was the only way to make the crisis concrete to the average U.S. citizen. After it became clear that saving a few cents at the pumps was proving a less-than-inspiring cause, Bush began backpedalling, insisting it's really all about standing up to aggression. But first impressions linger: Blood for Oil. Cadavers for Cadillacs.

The conservative answer to this has been on the order of ''Yeah, we're there for the oil. Want to make something of it?'' Or rather, not so much oil as property rights. If the U.S. really believed in keeping the oil flowing by whatever means necessary, it would have sent the troops in back in 1973. There's a difference between intervening to subvert the rights of resource-owners, even if it would mean access to cheap oil, and intervening to restore them. Without property rights, the whole international economy would collapse, which would destroy a great many more lives than a desert war.

But the proper response is this: If the U.S. is prepared to trade blood for oil, it's crazy - strictly as a matter of economics. In the first place, the surest way to drive oil prices to $100 a barrel is to start a war in the Gulf. In fact, it's not even worth sending the troops to prevent a war: even if Saddam Hussein were to have invaded Saudi Arabia, the cost in higher oil prices could not conceivably have justified the cost of military action.

Intervention has already cost the Pentagon US$2.5 billion; for the current fiscal year, the budgeted amount is US$20 billion - and that was before the latest call- up of 200,000 more troops. According to researchers at the U.S.-based Economic Strategy Institute, the real price of Middle East oil to the U.S., including all the military and aid expenses needed to secure it, is not US$18 a barrel, but nearly US$80.

WORLDWIDE BAN

That's not quite right, however. If the U.S. spent nothing at all to secure the supply of Mideast oil, prices would not jump to US$80. They probably wouldn't go much past US$18. If Saddam took over all of the Middle East, the effect would be the same as if the Organization for Petroleum Exporting Countries (or the Middle East contingent in OPEC) were to achieve perfect cartel discipline. But these are not the 1970s. Even a perfect OPEC has much less power to determine the world price of oil - assuming it had it even then - which in turn is far less important to the U.S. economy.

Given the state of his own economy, Saddam has no interest in just shutting down production. Energy economist David Henderson figures Saddam would maximize revenues at a production level just four million barrels a day below pre- crisis levels, which he calculates would lift prices to US$27 a barrel - less than they are now. As it happens, moreover, four million barrels is about the amount withdrawn by the worldwide ban on Iraqi-Kuwaiti oil. So even the embargo is a waste of time.

Suppose military intervention were needed to safeguard cheap oil. On hard- headed, callous, capitalist grounds that still wouldn't make sense. The supply of oil is, as we have seen, exceedingly insecure. That's no reason consumers should not have the option of buying oil vs more expensive energy sources, provided they are willing to pay the premium for that risk. By intervening to keep the oil flowing, however, the U.S. government is implicitly subsidizing oil consumption. Private agents should bear the costs of their own choices.

No, the whole thing is so irrational that the only conclusion is that Bush actually means what he says: that Saddam disqualified himself for office the moment he invaded Kuwait, that he cannot be left to add nuclear missiles to the chemical weapons already in his arsenal. Blood-for-oil just won't wash.