Boston — John B. Anderson must shortly make a big decision. What he doesn't know is whether anyone cares.
The 1980 independent presidential candidate says he must decide ''within the next few weeks'' whether he should form a third party to run a candidate in the 1984 presidential election. Presumably the candidate would be Mr. Anderson.
''I will have to . . . make a decision before the end of the year,'' he says. ''I plan to send out a fund-raising letter . . . to test whether there is financial support'' for a third-party effort, he says. If a new party is organized, then early in 1983 ''you come to the business of having a convention, formally nominating and accepting a candidate as the standard bearer and all of that.''
A clear obstacle to all of this, Anderson agrees, is the fact that he is politically invisible. In 1980, after 20 years as a Republican congressman from Illinois, he won the votes of some 5.5 million Americans in his presidential bid. Today he holds no public office, with its ready-made platform for media attention.
''I'm not so divorced from reality that I don't appreciate the difficulties, all of the doubt that many people will communicate, most of whom now are entrenched in one of the two parties and simply can't even think outside of that framework,'' he says.
''I think that the times are sufficiently singular that, yes, . . . there's a chance for a new party to be created.
''I think that when you've got 11 million people out of work, it's an astonishingly poor result to have only two-fifths (of registered voters participate). . . . I feel that the disillusionment (with the two existing parties) is pretty deep.''
Anderson is still an arresting speaker. He is particularly well-received, he says, on college campuses, a political landscape from which his 1980 campaign ''brought many people into the political process for the first time.''
For now, the once (and future?) presidential candidate is promoting a number of policies - including campaign spending reforms, military spending cuts, and the nuclear freeze - which presumably could shortly become a party platform.
Public financing of political campaigns, he says, is ''the only cure, the only Gresham's law that will drive out the bad money in politics today - the special-interest money.''
The 1982 congressional campaigns, he says, were ''disgraceful'' on two counts: ''from the sheer amount of money that was spent and from the clear, clear evidence that the political action committees (PACs) have got a lot on both the Republicans and Democrats.''
Votes in several states on the issue of a freeze on nuclear arms showed ''no clear evidence'' that the freeze has overwhelming public support, Mr. Anderson says. Nonetheless, he strongly and actively supports that movement.
Anderson says he would also like to see cuts in military spending much larger than those being talked about by either the Republicans or Democrats. ''I still think people are taken in by the argument that the Soviets were building, building, building during the '70s and that we did nothing,'' he says. ''We developed the cruise missile, we built the Trident submarine, we MIRVed 550 Minuteman III missiles, we had people working night and day to improve the defense forces of this country.''
Without big cuts in military spending, he says, ''we are not going to find the resources to do the things here at home that ought to be done. We're kidding ourselves.'' The US economy, he says, is undergoing a fundamental change from the so-called smokestack industries to high-technology and services. He disagrees with the Reagan administration's hands-off attitude, and says that government must assist in that change.