Spanish, including the Socialists, seem apathetic about politics

The Spanish Socialist Party, which in seven years jumped from a clandestine operation to power, starts a convention in Madrid tomorrow, its first since winning general elections in 1982.

After two years in power, the once little-known, long-haired party leaders who sang the ''Internationale'' with raised fist will face a different sort of music. The policies of Felipe Gonzalez's government - economic austerity, the unchecked rise of unemployment, and above all, the turnaround in favor of remaining in NATO - are bound to bring some fireworks from the radical left.

But the leadership is confident it can contain the criticism and any attempt to redefine the party's relationship with the government.

Although they received a record 10 million votes, the Socialists claim only some 150,000 active members.

Disinterest affects the other political parties as well. Hardly anyone boasts of being a member of a political party. This lack of involvement is a phenomenon that many see as the major failing of the young democracy.

The obvious historical reason is the civil war and 40 years of dictatorship during which the people were disconnected from political life.

Enrique Herzog Mugica, one of the ''historical'' militants of the Socialist Party and now a leading politician, cites another reason: ''Though Spaniards fought passionately for liberty and democracy, . . . there is no sense of getting together in associations and working together.''

But even the Franco years do not explain today's lack of involvement. A certain apathy and curious nostalgia for more difficult times are summed up in the expression: ''Under Franco we suffered better.''

Lina Galones, a Communist Party sympathizer, says wistfully: ''There is no longer the same feeling of common effort as there used to be during 'la clandestinidad.' People don't seem to care anymore.''

The old antagonisms that fed political fervor in the 1930s have disappeared. Eager not to upset the balance between political forces during the transition years, parties converged toward the center. ''Consensus politics'' has led to indifference.

The Socialist Party is the most obvious case in point. Government policies in both economic and foreign affairs have led to widespread disenchantment among party supporters. The party's organizers have made little real effort to recruit masses of active new members who might threaten their tight control of the party machine.

Victor Perez Diaz, a sociology professor at Madrid University, says: ''The university is ideal recruiting ground. Apart from a poster or two from time to time, nothing is done to attract the students to the party.''

Party spokesman Pedro Bofill says: ''Look at all the militants in office - what more do we want? It's not a bad thing if people turn to other associations that are growing up around the party.'' He points to parents participating in decisionmaking on school boards.

At present the main right-wing opposition party, the Popular Alliance, has more members than the Socialist Party, is actively recruiting more, and has done much to refurbish its image and to attract the young.

The party that has suffered most in all this is the Communist Party, which is now torn by internal strife.

''We have democratized the party structure, but in doing so, the wind has rushed in from all sides. We now need to find a common denominator among our different tendencies and recreate a party that can respond realistically to the people's needs,'' says Marcos Ana, a poet and active Communist militant. The Communists hope to regain a following with the pacifist movement and anti-NATO campaign. Since 1977, party membership has dropped from 200,000 to roughly 80, 000.

Not everyone sees the current disinterest in political parties as negative. Says sociologist Amando de Miguel: ''We give apathy a pejorative connotation. But presently in Spain it's not a bad thing that people are more interested in football and can afford to look elsewhere. It is a sign of a more developed country.''