LONDON -- The red flag has been furled. Neil Kinnock is socialism's white flag of surrender. The death of the socialist idea in its myriad forms is represented not only by the fall of East European regimes but also by the rise of Kinnock as the re-definer of Britain's Labor Party. He soon will have been leader of the opposition longer (since 1983) than anyone in British history.

It is said (even by some of his Labor colleagues) that he would be the most intellectually negligible prime minister since the 1832 reform bill began the broadening of democracy. He speaks with what friends call Welsh brio but what actually is the garrulousness of a mind through which winds blow. He is more prolix than Hubert Humphrey was, but without Humphrey's honest passions or serious purposes. His wife is seriously left-wing and severely anti-American, but he is Labor's post-socialist persona: amiability substituting for ideology.

A critic says Kinnock has the sort of problem with adjectives that alcoholics have with whiskey: overindulgence. But it is with nouns denoting substance that socialists nowadays are abstemious.

When Labor came to power after the war a party leader solved the definitional problem by saying that socialism is whatever a Labor government does. But there has been no Labor government to do anything for 11 years, and all that Kinnock says about what the next one would do amounts to (this from a bemused conservative) supply-side socialism. That is, it would do what all governments do -- spend on education, training, infrastructure -- only more of it.

Kinnock's task, to which he is sublimely suited, is to be so bland that conservatives seem overwrought when they say that electing a Labor government would be ''an act of national recidivism, squarely against the grain of the times.'' The grain of recent times has indeed run rightward in the nations with the three strongest capitalist economies (the United States, Germany, Japan). In the fourth strongest, France, reality quickly drove President Mitterrand off a socialist path eight years ago.

Nowadays Britain's gun-shy socialists confine themselves to statements that are false as history and vacuous as promises. For example, ''Our basic stance should be that there is nothing inherently unsocialist about the market mechanism . . . if properly regulated and monitored.''

However, Labor occasionally commits the sin of specificity, as when proposing that ''the lowest-paid worker will receive an hourly rate of not less than two-thirds of that received by the male median full-time worker.'' So a ''properly regulated and monitored'' labor market would aim for the old egalitarianism that produced an economy with ''the British disease'' and then three consecutive conservative governments.

Kinnock trots out the tired old praise of Sweden's ''middle way.'' Such praise is not much heard in Sweden nowadays, and anyway Sweden is clearly a capitalist society, albeit one suffocating beneath statism. A plausible criticism of conservative policies -- that in the name of consumer sovereignty they have produced too much consumption and too little investment -- sounds, when coming from socialists, even from the reformed sort, like a coded call for ''planning,'' the old socialist dislike of any social result that is not compulsory.

Down the years the label ''socialism'' has denoted a multitude of sins, but in Western Europe it has always been, for middle-class adherents, a rationale for editing and improving the tastes of the masses. But aside from censorious intellectuals, socialism has had far too few middle-class adherents.

The very name of Kinnock's party -- Labor -- testifies to a wrong turn socialism took long ago. The study of socialism is now almost entirely retrospective and focused on failure. This is partly because of developments early in the century.

Both theory and practice -- Marxism's identification of the industrial proletariat as the engine of history; and worries about the working class defecting to communism -- caused socialist parties to define themselves on a class basis. Thus the socialist movement became self-consciously working-class and turned into a cul-de-sac. Capitalism did not produce an ever larger and more militant working class. Capitalism did not even guarantee a perpetual majority of industrial workers.

Today, a fashionable formulation, earnestly discussed by what remains of the socialist intelligentsia, is ''Fordism,'' a category coined long ago by an Italian communist. We live, say today's socialist thinkers, in a post-Ford period.

Henry Ford pioneered production with large industrial units served by armies of unskilled or semi-skilled workers. But then came affluence, product differentiation, market research, advertising, packaging, design. All these produced fragmentation, disaggregation, practical and ideological emphasis on smallness, freedom, privacy and choice.

In short, there has been a rebellion against statism and bureaucracy and regimentation. ''In a word,'' says a leftist realist, ''Thatcherism.''