A proposal to slow development of space weapons essential for protecting U.S. intelligence and communications in an all-out war is expected to go before President Carter soon in presidential review memorandum (PRM) 23.

Although finishing touches have not yet been put on PRM 23, the thrust of the inter-agency study is certain at this writing. If will seek to lead the President away from the Ford administration's push for swift development of outer-space weaponry.

The importance of developing top-secret technology to defend against possible Soviet attacks on U.S. satellites would seem obvious on its face. A Soviet attack destroying communication and spy satellites would leave the U.S. helpless. Nevertheless, the arms-control lobby, now riding high with Paul Warnke as director of the Arms Control and Disarmament Agecy (ACDA), looks to outer space for an early test of the Warnke thesis on arms control.

Warnke's thesis: The United States should unilaterally abandon new weapons systems as an example to the Russians, assuming the Kremlin would then follow that example. This thesis, unsupported as yet by an evidence during the past 30 years of U.S. Soviet relations, would be applied at once to outer-space warfare - if the President accepts the thrust of PRM 23.

In its dying days, the Ford administratiion conducted two secret studies into how the United States should respond to alarming Soviet advances in the technology of offensive outer-space warfare - satellite-killing Soviet satellites, sometimes called satellite interceptors. The Ford answer: full speed ahead for the United States.

A footnote: Compounding the U.S. danger was the conviction last spring of two Americans on espionage charges in TRW's top-secret weapons plant in California. They were charged with passing to Moscow this nation's most advanced outer-space warfare technology, immediately making U.S. satellities more vulnerable to potential Soviet attack.

Treasury Secretary W. Michael Blumenthal traveled first class on his round trip to Paris for an Aug. 6 International Monetary Fund meeting, an obscure fact that helps explain a philosophical conflict over tax reform within the Carter administration.

Blumenthal billed the government for his higher-priced seats to save physical wear and tear flying across the Atlantic Aug. 4 and returning Aug. 7. Why, then, should not a businessman continue to get a tax deduction equal to the full cost of first-class tickets? Blumenthal says he should.

But influential aides at the White House strongly disagree. They support Sen. Edward Kennedy's long-standing proposal to permit tax deductions only of tourist-class fares. What's more important, President Carter feels the same way.

Similar disagreements abound. Blumenthal is skeptical about other Kennedy-style proposals - such as crackdowns against expense-account business luncheons and interest deductions on vacation homes - that would cause irritation without generating much tax revenue.

But the mood at the White House is set by the President. "I know they really don't amount to much, but Jimmy wants them," a key presdiential adviser told us. So, the bill to be sent to Congress by Oct. 1 is expected to reflect Jimmy Carter more than Mike Blumenthal.