The 1980 Democratic platform takes familiar liberal positions on issues of human welfare and civil rights -- except in cases that might involve the sudden expenditure of large sums of federal money.

The platform is filled with "pledges" and "commitments" to continue expanding federal support for programs that help needy Americans, but the pledges are vague. Given the option (by supporters of Sen. Edward M. Kennedy) to come out for speedy adoption of comprehensive national health insurance, though, the convention today voted no.

Instead, the platform calls for enactment of a "universal national health insurance plan," but suggests no legislative package of timetable. So the Democrats can say they favor national health insurance, but President Carter can add that fiscal restraint is essential, and comprehensive health insurance will have to wait.

Despite this fiscal caution, though, the Democratic platform commits the party to a long list of liberal positions that contrast sharply with the positions the Republicans took in Detroit last month.

For example, the Democrats support ratification of the Equal Rights Amendment, which the Republicans decided to oppose. The Democrats support the right to have abortions, while the Republicans favor a constitutional amendment to ban abortions.

The Democrats adopted the first endorsement of "gay rights" to appear in any American political platform. The relevant passage opposes discrimination on the basis of "sexual orientation."

Gays are only one of many interest groups whose causes are endorsed in the platform. So, too, are the rights and concerns of ethnic Americans. Puerto Ricans, American Indians, Americans living overseas, the handicapped and, of course, blacks, Hispanics and women.

The Democrats declare that "an effective affirmative action program is an essential component of our commitment to expanding civil rights protection . . ." Ronald Reagan, the Republican nominee, has tried to avoid taking a position on affirmative action programs.

The platform also contains planks on civil liberties and privacy that call for stronger protections of both, including federal action to overturn a recent Supreme Court decision permitting police seizure of newspaper notes in some circumstances.

The platform contains long sections on elderly Americans and Social Security. In includes this passage:

"We hereby make a convenant with the elderly of America that as we have kept the Social Security trust fund sound and solvent in the past, we shall keep it sound and solvent in the years ahead."

The platform declares that "all Americans, regardless of age, must be afforded an opportunity to participate in the mainstream of society."

Welfare reform is dealt with in a compromise plank worked out by Kennedy and Carter forces. It calls for federal takeover of cities' welfare costs and an immediate reduction in state welfare obligations. The platform contains a strong, detailed endorsement of federal welfare programs, including food stamps. The Democrats say that "significant expansion" of cash assistance to poor people to help them cope with the rising cost of energy "is urgently needed."

The platform includes a long section on education, which President Carter intends to make a major issue in the fall campaign. The Democrats boast of large increases in federal aid-to-education programs during the Carter administration, adding, "We favor a steady increase in federal support."

The education section includes endorsements for numerous special-interest concerns, including "an effective bilingual program," educational opportunities for the handicapped and American Indian education.