YOU CAN APPRECIATE the Russians' bewilderment. From their not inexpert reading of Jimmy Carter's pre- and post-election supporters, words and advisers, they thought they had someone with whom they could get back on the track of detente. It then turns out that in style (erratic, highly personal), in concern for human rights (often crudely interventionist) and in approach to arms control (ambitious, demanding), they have an unfamiliar and unsettling figure determined to do things in his own manner. Throw in the extra immobility created by the onset of another Kremlin succession struggle and you can see why Leonid Brezhnev himself, obviously frustrated to see his detente policy slipping away, comes forward to demand - almost to plead - that Mr. Carter change his ways.

Mr. Brezhnev has a point. For whatever may be said about any single strand of the Carter policy, it is undeniable that the President has proceeded in excessive haste, without waiting until his foreign-affairs team was in place and ready, without considering how the pieces might fit, without due regard for Russian reaction. Only now, for instance, is there being completed the overall strategic study that, one would have thought, would have been the prologue of policy, not an appendix. Recently the administration has begun to suggest that its policy, far from being improvised, flows from a calculated, integrated plan. Perhaps so. But the look of it has been slapdash. Even many people sympathetic to Mr. Carter's specific purposes feel that his approach has been flawed and self-defeating. It goes without saying that the Russians are doing what they can to propel this feeling along.

Mr. Carter came to the White House promising to be a tougher bargainer than his predecessors, and no doubt the temptation is strong to demonstrate to the Russians that he is not as capricious, or as movable, as they suggest. Given the resonance of the nationalist chords he has struck in the American public, it may even be good politics, at least for a while. What he must now determine, however, is whether there are not ways in which he can settle the Russians down without compromising his essential goals in this country's relations with the Soviet Union. These are, or ought to be arms control, keeping the struggle for influence in third countries under control, and - most sensitively - building conditions in which Moscow will not feel that, by treating its own citizens halfway decently, it is losing face.

A summit would be a good place to make an adjustment. But the Russians are resisting a summit, apparently fearing that Mr. Carter would use it not for adjustment but to apply more pressure on human rights and other matters as if in a brass-tacks negotiation. We cannot believe, however, that Mr. Carter is so dogmatic and self-righteous about tactics that he is unable to make the transition from the introductory round of his foreign policy to a second stage of consolidation. It is partly a matter of style. But style, of course, can have profound effects on matters of substance.