Here we go again.

China (like some NATO nations, and Saudi Arabia) is acting as though it is doing America a favor by having mutually advantageous relations with America. China says the American proposal to sell arms, and especially the FX advanced fighter, to Taiwan is "a severe test" of whether America "truly values" relations with China.

Even in the State Department there is no obsession as incorrigible as the obsession of some persons with placating Peking. In December some members of that faction sent Secretary of State Haig the sort of awful memo he should have rejected with his famous testiness. It concerned "how to move urgently toward resolution of the Taiwan arms sales problem in light of the Polish crisis."

Seizing upon Poland as a pretext for doing what this faction is determined to do anyway, they suggest sending a delegation of themselves to urge the Chinese to do unspecified things against Russia. But, they say, the delegation's success would depend on a "favorable" (that is, unfavorable to Taiwan) decision on the FX. By "removing the specter of the aircraft," America could prevent a "precipitous Chinese reaction" to even the sale of spare parts to Taiwan, which could "unravel" and "rupture" U.S.-China relations. There should be no sales "exceeding Carter levels."

These dispensable (but, alas, not dispensed with) Carterites now serving Haig are urging Carter's policies on Carter's successor. They must think President Reagan does not remember candidate Reagan noting that Congress, "reflecting the strong support of the American people for Taiwan," forced changes in Carter's proposed Taiwan Relations Act. Carter's proposal did not even mention defense cooperation with Taiwan. The final act (Congress' preemptive leash on the State Department's appeasement reflex) committed America to providing Taiwan with defense arms "in such quantity as may be necessary to enable Taiwan to maintain a sufficient self- defense capability." This act obligates the president and Congress to determine appropriate arms "based solely upon their judgment of the needs of Taiwan." That is, based only on Taiwan's needs, not at all on Peking's desires.

Opponents of the sale argue that even with the FX, Taiwan's air force (currently 390 combat aircraft) could be overwhelmed by China's 5,000 combat aircraft. But it is tendentious to disregard the fact that deterrence is a function of the potential costs of aggression. And it is perverse to argue that because Taiwan is vulnerable, America should make it more so.

China is too backward, economically, to cure its military weakness without the West's capital and technology. U.S.-China relations are rooted in that need, and in China's geography and culture (including ancient national and relatively recent ideological animosities that make it a counterweight to Russia). China is not apt to "rupture" relations with the United States in a fit of pique about an arms sale that is a matter of compliance with American law.

Candidate Reagan said: "I'm sure that the Chinese leaders would place no value on our relations with them if they thought we would break commitments to them if a stronger power were to demand it." Precisely right: by conforming to China's dictates regarding U.S.-Taiwan relations, America would prove that it is too pliable to serve China's interest in a cooperative balance of power against Russia.

Furthermore, the State Department's advocates of Peking's position are caught in a contradiction: if Reagan's refusal to allow Peking to veto American compliance with American law could cause an "unraveling" of U.S.-China relatns, then those relations are too superficial to be important. The idea that selling FXs might provoke a rapprochement between China and Russia implies, implausibly, that the split is trivial, and that U.S. policy controls China's internal power struggle. This is a version of an apparently unsinkable fallacy, usually heard in this form: we must appease Moscow, lest the "hawks" lurking in the Kremlin's closets come to power.

The Taiwan issue waxes and wanes inversely with China's confidence in America as a partner against Russia. It waxes now in the wake of the Reagan administration's feeble response to Poland's crisis. Countering Russia is China's top priority, but if America is unserious about that, China probably reasons that it might as well gain ground on the relatively trivial issue of Taiwan.

Having sold to the uncooperative Saudis AWACS they did not need, Reagan will mock his past and undermine his future if he denies an ally aircraft it really needs. Peking recently failed to intimidate the Netherlands from selling two submarines to Taiwan, and then reduced its diplomatic representation in the Netherlands. America should be as unintimidated as the Netherlands, and should then see if Peking values relations with America as little as it values relations with the Netherlands. If Reagan does not sell the FX to Taiwan, he will have produced what he was elected to prevent: the continuation of Carterism.