West European leaders are approaching this week's economic summit in London with a perspective very different from that of the Reagan administration. The Europeans are worried that the White House sees the gathering as an opportunity, essentially, for them to say ''thank you'' for the American economic recovery.
They themselves, however, see the recovery as fragile. They especially want to talk about how high American interest rates are deepening a world debt crisis that, they believe, demands urgent action.
The four European countries attending the meeting - Britain, France, West Germany, and Italy - are concerned that Washington does not accept the need for urgent measures and is not prepared to discuss these issues at the summit. Instead, behind the Reagan White House's trumpeting of a ''summit of peace and prosperity,'' they see crude election-year public relations.
Hence, the Europeans have only the most modest of expectations for the meeting that opens Thursday.
''We're just considering this a personal meeting to exchange ideas,'' a top French official confides. ''It's not really a place to make decisions.''
In contrast, European officials do not tire of pointing out that the third world's international debt is moving toward a total of $1 trillion. The dangerous results of this load, they add, have become abundantly clear in the past few weeks.
In April, there was the 11th-hour bailout of Argentina, arrears in its international loan payments, by a group of Latin American neighbors. Then in May , Continental Illinois Bank was bailed out by the United States government. Also , Bolivia and Ecuador announced they were suspending repayment on their foreign debts. And American interest rates moved up for the first time in 18 months. As a result, the Europeans, with nuances differing from country to country, detect the possibility of a crisis along the lines of 1929.
''The events are a good proof for our point of view,'' the high-ranking French official said.
The European point is that high American interest rates are making the debt crisis unmanageable. European complaints about the high American rates are nothing new. But the argument is different this time. Whereas ministers once grumbled that the rates were choking off recovery in the developed world, now they stress the danger in the third world.
Even British Prime Minister Margaret Thatcher, perhaps the most conservative, pro-Reagan of European leaders, said last week that high interest rates are ''making things extremely difficult'' for heavily indebted countries.
Other Europeans less sympathetic to Mr. Reagan draw the argument much further. They say American interest rates will continue to rise unless the US budget deficit is lowered. Then, possibly, a major Latin American country will default. Some banks could go under in Europe and the US, and no one will be able to rescue them. World's stock markets could collapse.
''The US is making a critical historical error'' in allowing third-world debts ''to snowball'' because of rising interest rates, the French official said. Even if the nightmare scenario he outlined could be avoided, he explained, by choking off development in the poorer countries, the richer countries who need them as markets will also be hurt. In the long run, this pressure could turn many countries violently against their Western creditors.
Perhaps the European doomsdayers are exaggerating. In any case, despite their fears about the world economy, the Europeans don't see much point in losing their tempers when they sit down with President Reagan in London.
Faith in such big-power economic summitry may be declining in Europe. The meetings have grown into news media spectacles. Often overwhelmed by immediate crises, they are seen as producing few long-term results.
Two years ago, for example, there was talk here of setting the world right at the Versailles summit. Instead, the Israelis invaded Lebanon while the heads of state were meeting, and the leaders themselves agreed to disagree on trade with the Soviet bloc.
The summits have also become crude political forums. French President Francois Mitterrand saw the Versailles summit as a opportunity to enhance the legitimacy of his government. Mrs. Thatcher used her presence at last year's Williamsburg summit as an effective campaign device. And Mr. Reagan seems prepared to do the same this year.
It is not a bad thing that the seven leaders meet, the Europeans say, but it is not crucial either.
''Don't expect miracle solutions,'' Mrs. Thatcher warned at last week's pre-summit press conference. ''Blessed is he that expecteth nothing, for he shall not be disappointed.''