What's ahead for Britain in the 1980s?; :Is Britain Dying? (perspectives on the Current Crisis). Edited by Isaac Kramnick. Ithaca, N.Y., and London: Cornell University Press. $15.; :Suicide by Socialism, by Minden Blake and H. J. Weaver, London: Springwood Books. L5.95.

* Inflation: up to 27 percent a year after Labour took office in 1974, and up again to 20 percent now that the Tories have assumed power. * Industrial decline: from second place in the World Productivity League in 1953 to 20th out of 24 industrial nations in 1979.

* Mass unemployment: now nearly as bad statistically as it was in the Great Slump of the Thirties.

* Strikes: the steel strike may prove to have been of seminal significance.

This is how Great Britain appears as it faces the probability of a worldwide recession in the early 1980s -- a country seemingly saved from total collapse only by the great wealth of oil bubbling up from beneath the North Sea.

And this is what prompted Cornell University to hold a conference of distinguished academics, plus two British politicians, in April, 1978, from which "Is Britain Dying?" is derived.

Great Britain's power and reputation have sunk together, as editor Isaac Kramnick points out, yet what happens to this country still matters crucially -- not only to the United States but to the whole of the world outside the communist bloc.

Edward Heath, former Tory prime minister, denies that there is in fact a specifically British problem at all. He sees the trouble as worldwide, soluble only through a joint program for economic growth to be agreed between the European Community, the United States, and Japan.

Barbara Castle, onetime Labour cabinet minister and now a Member of the European Assembly, also thinks it is a world problem. But she offers different solutions -- protectionism for Britain, reduced consumption, increased industrial investment, and a retreat from the EEC.

Were he around today, Lord Keynes, the great liberal economist, might see nothing but darkness -- and indeed, there is a great deal of dark anxiety in this book. Several contributors talk of the possible breakup of the United Kingdom, having misjudged the force and thrust of Scottish nationalistic fervor. Others have been led to take seriously the antics of the far-out, neo-fascist, entirely incredible National Front.

Only Stanford's Peter Stansky, weaving his comments around the attitudes of George Orwell's "1984," sees a hope that in actual fact, "England may soon be leading the way, demonstrating how it is possible to live humanelym in a postindustrial, postmodern age."

Possibly all of us are going to be surprised by time, for something of very great import to the whole Western world is happening now in and to Great Britain. And it is perhaps the book's only great weakness that the thought behind Margaret Thatcher's government and its policies is entirely unrepresented here.

"Suicide by Socialism," by a former businessman turned inventor, and a political economist who became a journalist, presents a penetrating but more lightly written analysis of Britain's troubles.

Socialism, these authors say, is to blame for the nation's decline. But they define "socialism" in a somewhat individual way. To them Mr. Heath is highly socialistic, while Sir Harold Wilson is quoted with approval, as is the economic record of Sweden.

What they blame for Britain's troubles is a collectivist philosophy that has produced a high-tax, low-productivity economy (much welfare but little incentive , proliferating bureaucracy but declining industry), with progress thwarted by a powerful trade union movement convinced that there is only so much work available and that therefore it must be shared equally.

Nevertheless, the authors are optimistic about the future: "There is no reason why, within a decade, everyone in Britain should not be twice as well off in real terms as they are now."

Far from academic -- and quite an important book.