James J. Kilpatrick overlooked several fundamental points in his column on the minimum wage {op-ed, July 15}. First, 7 million workers today are paid at or below the minimum wage. Working full-time, year-round, a minimum-wage worker earns $2,100 below the poverty threshold for a family of three. Keep in mind that half of these 7 million workers are 25 or older. Further, Census figures on poverty show 2 million workers (including 1.2 million heads of household) work full-time year round but are confined to a poverty existence.

Fifty years ago, when the minimum-wage legislation was enacted, it was founded on the basic equitable principle that every worker should be paid enough to achieve a decent minimum standard of living. Virtually every year from the law's adoption until 1981, when the last adjustment went into effect, earnings of minimum-wage workers were sufficient to reach this level. Using the government poverty threshold as a criterion during the '60s and '70s, income from a minimum-wage job averaged more than the poverty line for a family of three. But in the past six years, with the minimum frozen at $3.35 an hour, annual earnings from a minimum-wage job have fallen steadily farther below the government poverty level. Thus, in 1987 a worker earning the minimum wage has an income 23 percent lower than the poverty figures.

The second fundamental principle behind minimum-wage legislation that Kilpatrick ignored was that even the lowest-paid worker should be paid no less than one-half the wage paid to the average worker. Here again, this historical relationship has been eroded. During the '50s and '60s, the legislated minimum averaged more than 50 percent of the average wage. In the '70s it dropped slightly to about 46 percent. But in the '80s, it has continued to decline, and now stands at less than 37 percent of the average wage.

Kilpatrick repeats unsubstantiated statistics that a higher minimum wage will cause serious unemployment. These arguments are not new. Congress has debated and adopted measures that raised the minimum wage 14 times over the years, and industry groups have vigorously opposed the increases. Their argument was, and continues to be, that hundreds of thousands of workers, particularly youth, will be laid off if the minimum wage is raised. But the facts demonstrate such claims are baseless.

In 1977, when Congress was considering increasing the minimum wage, the U.S. Chamber of Commerce estimated that 391,000 teen-agers would lose their jobs. The actual result? Teen-age employment rose by 382,000 in 1978 despite an increase in the minimum wage from $2.30 to $2.65 per hour. In 1979, when the minimum was raised again, teen-age employment showed a further increase.

Clearly, other factors such as economic growth, interest rates and inflation have a far more profound and significant impact on employment than does the minimum wage.

That fact was noted by Prof. F. Gerard Adams of the Wharton School when he said in congressional testimony that minimum-wage increases would have only minor effects on broad economic trends. "These are tiny, largely imperceptible differences, and they will be overwhelmed by small changes in any one of the number of more important variables (interest rates, exchange fluctuations, trade and fiscal deficits, energy prices, etc.) which are likely to affect the economy over the next three or four years."

Using the Wharton School's model of the economy and factoring in the higher minimum-wage proposal in pending legislation, Adams found that over a three-year period, raising the minimum wage would increase the unemployment rate by less than 0.1 percent.

"Our calculations suggest that estimates of large job losses and dire consequences to the economy as a result of raising the minimum wage do not stand up to scrutiny," Adams said. "The costs of a minimum wage increase to the economy as a whole will be small in the aggregate and imperceptible to the individual. The gain will be a return to the standards of wage equity which originally inspired minimum wage legislation 50 years ago."

The Kennedy-Waxman bill to raise the minimum wage would simply, as an act of fairness and justice, bring the compensation of 7 million workers back up to the 1982 level over a period of three years. Surely we should not permit concern over Kilpatrick's admittedly "hypothetical" case to stand in the way of our making this significant contribution to the problems of the working poor.

The writer, who was secretary of health, education and welfare under President Eisenhower, is cochairman of the Citizens Committee for a Just Minimum Wage.