It is correct that, on the whole, the Democrats like President Reagan's new foreign policy better than the Republicans do, but the gloom over there is that there aren't a lot of Republicans around who are going to vote Democratic in 1988 because they are sore at Reagan about INF. So what are they going to fuss and fume about come next summer in Atlanta?

The Rev. William Sloane Coffin, newly ascended to the presidency of SANE/Freeze, which is the organization specializing in nuclear discontents, said solemnly the other day (I kid you not) that Soviet reporters here in connection with the summit conference last week were ''shocked'' at the condition of the homeless in New York. Someone pointed out that just as it is true that Cubans recently risked their lives to prove that they preferred to be in prison in America than at large in Cuba, many of the homeless of New York live in relative luxury by contrast with Muscovite life in middle-class apartments. The homeless are a continuing problem, but an attack against homelessness has got to be done in context of the knowledge that, in a free society, you cannot abolish Skid Row.

So what else? Paul Manheim, an elderly, shrewd and amusing attorney with an eye for figures, recently addressed a letter to the executive editor of The New York Times, Max Frankel. The letter was written in the ironic mode (''When are you going to start giving your readers the truth?'') and such letters are seldom calibrated with attention to the nicer distinctions, but there was much robust truth in Manheim's Manifesto, truths from which Republicans will get much nourishment in the forthcoming national debate.

Manheim wants to know why the readers of The Times, among others, are under the impression that the Reagan administration has cut social services, generally speaking. It remains true, after all, that there are more than 1,000 social services provided by the federal government, but the particular point is arresting. In Jimmy Carter's last year, spending for such services totaled $381 billion. Now advance $381 billion to compensate for inflation to the year 1987, and you arrive at the figure $507 billion. That's how much Reagan would have spent if he had spent an amount comparable to Carter's. In fact, he spent $581 billion. Up almost 20 percent.

And the eternal question of taxes. It is a part of the liberal legend that the reason we suffer so huge a deficit is that Reagan has ''reduced'' taxes. Well, Reagan did reduce the ''rate'' of taxation, which is very different from reducing taxes. Indeed, it is a documented part of one aspect of supply-side economics that taxes often increase after rates are lowered -- and indeed, because they are lowered.

It would certainly appear to have been the case under Reagan. In Carter's last year, tax revenues were $517 billion. Apply the inflation factor, and one would expect taxes, assuming the rates had stayed exactly the same, to have been $689 billion in 1987. But under Reagan, tax revenues were $857 billion. That's $168 billion more revenue than under the high tax rates. That story tells us a lot about revenue, a lot about social philosophy and worlds about those Democratic candidates who, like former governor Bruce Babbitt, like to stand up on tiptoes to prove that they want tax increases.

There is the matter of the trade deficit. We all deplore it. We all suffer at the mere thought of it. We all indite in bloody letters the results of it. And then we look about us. Our exports in 1980 came to $226 billion ($301 billion in 1987 dollars). In 1987, our exports ($207 billion) had relatively declined, which would cause the loss of jobs, correct?

But quite the opposite happened. Not only did unemployment reduce as a percentage (from 7.1 percent in 1980 to 6.3 percent so far in 1987), it actually went down in absolute terms. The figures here are startling: in 1980, 101 million Americans had jobs; the figure today is 114.5 million.

But surely individual industries were hurt, conspicuously the automotive industry, given everybody's apparent preference for European and Japanese models? In 1980, 1,576,000 people were employed by the American automotive industry. Today, that industry employs 1,745,000 people. It's awfully hard on the Democrats when the party of depression brings on a decrease in inflation, a decrease in interest rates, an increase in federal revenues and a decrease in unemployment.

Well, perhaps NATO will unwind, and the Democrats can point the finger at Reagan and say: He did it! Hooray.