Sometimes I sit down to write a column brimming with passion. Sure of myself, firm in my conviction, I bang the thing out only to discover in the course of writing that I am wrong. So I rewrite, tone it down, change the conclusion and then have it published. Invariably, readers sense that something is wrong. The words say one thing, their vibrations something else. In the end, it's the vibrations that count.

I offer my own experience as something of a metaphor for the Reagan administration and its positions on race. Time and time again, it has been careful with its words, documenting its positions on everything from the voting rights act to the regime in South Africa with precise language, research and, of course, an ideology that is, on the face of it, totally nonracist. Yet, somehow a different message comes through. Once again, it's the vibes.

In the case of the Reagan administration, the vibes come from the president himself. In the course of a radio address or a press conference for which he has been well rehearsed, he might offer a cogent explanation of his policy toward South Africa or voting rights or even why his administration once thought that a college with racist policies is entitled to tax-deductible status. But sooner or later, something slips out that shows the president's position to be something other than learned or rational.

Recently, for instance, the president offered some praise for the South African regime: "They have eliminated the segregation we once had in our country -- the type of thing where hotels and restaurants and places of entertainment and so forth were segregated. That's all been eliminated." Not quite. Segregation of the Jim Crow variety persists in South Africa, but even its total elimination would hardly matter when blacks are not accorded citizenship and cannot, accordingly, vote.

Once in a column, I suggested this sort of thing reflected a kind of racism. For that, an administration official upbraided me, saying the charge of racism had become the new McCarthyism. I think he had a point. Certainly, the term has been cheapened by overuse.

So then what, exactly, is Reagan? The frank answer is that I am not sure -- and I'm not all that sure it matters. The fact remains that his career is replete with utterances on a par with the one he made about South Africa. This is a president who has opposed every civil rights bill that has come down the track. This is a president who recently concluded that the regime in Pretoria and Bishop Desmond Tutu are equally deserving of criticism. In short, this is a president whose offhand remarks and long-held convictions say one thing -- regardless of what is asserted in his behalf by others. The man has a manifest antipathy for the underdog, for the underprivileged. Just about the only thing he gets worked up about is high taxes for the rich.

Other Republicans understand the vibes that Reagan sends out on the issue of race. Some of them merely cringe when the issue is raised, others have taken pains to disassociate themselves from the president. Bob Dole's recent attempt to set the matter straight on voting rights is an example of that. But the president is the president. He sets the tone for his party, and no Bob Dole or Jack Kemp can make a significant difference.

Recently a group of presidential scholars met in New Orleans and tried to assess the Reagan presidency. There was the usual difference of opinion, but some thought Reagan would certainly rank high among presidents. This is the assessment of scholars. They read the words. This would not be the assessment of American blacks. They feel the vibes.