President Reagan last night promised the start of "brighter days" for the ailing economy, noting that the second installment of the three-year individual income tax cut he pushed through Congress last year takes effect today, along with a 7.4 percent cost-of-living increase in Social Security benefits.

"Too many Americans are still hurting," the president acknowledged in an opening statement at his news conference. "But we are beginning to make progress," he said.

"If we stick to our plan, if we keep the Congress from going back to its runaway spending, the recovery will take hold, strengthen and endure."

Reagan, who in the past said it was too early to blame him for the economy because his policies had yet to take hold, last night seemed to begin to accept responsibility.

He boasted of the decline in inflation since he took office, saying that because of this "the buying power of Americans is growing for the first time in years."

Reagan had no role in the Social Security benefit increase, which came automatically under a law passed in 1972. He mentioned it nevertheless, partly in an apparent effort to respond to Democrats who have said he wants to cut Social Security. "I've said . . . we'll protect those benefits and . . . the integrity of Social Security. We are honoring those promises," he said.

He called the tax cut--a 10 percent reduction in rates in all income tax brackets--"the keeping of another important commitment." It has been a central element of his economic program, though now some of his advisers seem more hopeful that households will spend it rather than save it as they first envisioned.

The tax cut will cost the Treasury about $30 billion over the next 12 months. But the take-home pay of most taxpayers will rise only a few dollars a week, and the cut has been criticized as favoring the wealthy, in that only for those in the highest income brackets will it be enough to offset the effect of inflation, which tends to move households into higher tax brackets each year, and the Social Security tax increases scheduled Jan. 1. (Details, Page D11.)

Reagan sought to meet this criticism in his statement. He noted some critics want to rescind next year's third installment of the tax cut and said "with their notion of fairness, low- and middle-income Americans would lose nearly 40 percent of their entire tax reduction."

By contrast, "Our loyalty lies with little taxpayers, not big tax spenders," Reagan said.

Reagan also attempted again last night to counter the damaging perception that he is insensitive to the concerns of minorities and women, and showed favoritism toward the well-off when he proposed special tax breaks for parents of children in private and parochial schools.

Reagan said the overwhelming majority of those who would benefit from this proposal are families with incomes under $25,000, and he noted pointedly that 40 percent of the students in Chicago's Catholic schools are black.

"We aren't taking anything away from the public school system," Reagan said. "What would hurt the public school system is if all of the independent schools closed and those thousands and thousands of youngsters were dumped on the public school system, which doesn't have the facilities or the means to take care of them."

Reagan fairly bristled when a reporter noted that black leaders were again questioning his commitment to civil rights, saying that he had only belatedly embraced the extension of the Voting Rights Act, which he signed this week.

"I know that some of those civil rights leaders have that impression" of his commitment, "and, as a matter of fact, they are doing a little bit of image buiding about me," Reagan said. "I would like to have any one of them point to a single instance with regard to me that supports their idea that in any Reagan Calls 'Case Closed' on Haig Departure 'Brighter Days' Promised For the Ailing Economy By Herbert H. Denton Washington Post Staff Writer

President Reagan last night promised the start of "brighter days" for the ailing economy, noting that the second installment of the three-year individual income tax cut he pushed through Congress last year takes effect today, along with a 7.4 percent cost-of-living increase in Social Security benefits.

"Too many Americans are still hurting," the president acknowledged in an opening statement at his news conference. "But we are beginning to make progress," he said.

"If we stick to our plan, if we keep the Congress from going back to its runaway spending, the recovery will take hold, strengthen and endure."

Reagan, who in the past said it was too early to blame him for the economy because his policies had yet to take hold, last night seemed to begin to accept responsibility.

He boasted of the decline in inflation since he took office, saying that because of this "the buying power of Americans is growing for the first time in years."

Reagan had no role in the Social Security benefit increase, which came automatically under a law passed in 1972. He mentioned it nevertheless, partly in an apparent effort to respond to Democrats who have said he wants to cut Social Security. "I've said . . . we'll protect those benefits and . . . the integrity of Social Security. We are honoring those promises," he said.

He called the tax cut--a 10 percent reduction in rates in all income tax brackets--"the keeping of another important commitment." It has been a central element of his economic program, though now some of his advisers seem more hopeful that households will spend it rather than save it as they first envisioned.

The tax cut will cost the Treasury about $30 billion over the next 12 months. But the take-home pay of most taxpayers will rise only a few dollars a week, and the cut has been criticized as favoring the wealthy, in that only for those in the highest income brackets will it be enough to offset the effect of inflation, which tends to move households into higher tax brackets each year, and the Social Security tax increases scheduled Jan. 1. (Details, Page D11.)

Reagan sought to meet this criticism in his statement. He noted some critics want to rescind next year's third installment of the tax cut and said "with their notion of fairness, low- and middle-income Americans would lose nearly 40 percent of their entire tax reduction."

By contrast, "Our loyalty lies with little taxpayers, not big tax spenders," Reagan said.

Reagan also attempted again last night to counter the damaging perception that he is insensitive to the concerns of minorities and women, and showed favoritism toward the well-off when he proposed special tax breaks for parents of children in private and parochial schools.

Reagan said the overwhelming majority of those who would benefit from this proposal are families with incomes under $25,000, and he noted pointedly that 40 percent of the students in Chicago's Catholic schools are black.

"We aren't taking anything away from the public school system," Reagan said. "What would hurt the public school system is if all of the independent schools closed and those thousands and thousands of youngsters were dumped on the public school system, which doesn't have the facilities or the means to take care of them."

Reagan fairly bristled when a reporter noted that black leaders were again questioning his commitment to civil rights, saying that he had only belatedly embraced the extension of the Voting Rights Act, which he signed this week.

"I know that some of those civil rights leaders have that impression" of his commitment, "and, as a matter of fact, they are doing a little bit of image buiding about me," Reagan said. "I would like to have any one of them point to a single instance with regard to me that supports their idea that in any way I am racially prejudiced or am not in full accord with providing civil rights for all our citizens. And that goes back before there was a term called 'civil rights.' "

Reagan claimed credit for appointing more minorities to executive and policy-making positions than any of those who preceded him as governor of California, and he said he thought the same was true for his appointments of women.

But he did not respond directly when a reporter, saying he was posing a question raised by the president's oldest daughter, Maureen, asked why had he reversed himself and opposed the Equal Rights Amendment after having supported it when he was governor.