TO BE FAIR about it, President Carter's decision on shoe exports was about the best that he could hope to get away with. If he had given the aggrieved shoe industry any less protection, he would have run a very large risk of being overridden in Congress. That would have put in force the federal Intenational Trade Commission's highly restrictive and grossly inflationary recommendations. It was worth giving up a bit of principle to avoid that danger. Instead, Mr. Carter has dodged and ducked around, leaving the key details of the future restrictions up to negotiation with the exporting countries. You might call it the least unfortunate outcome possible in this thoroughly unfortunate case.

Whatever relief it eventually brings to the domestic shoemakers, it won't be free for the rest of the country. It will mean fewer choices for American shoppers,and higher costs - particularly at the low end of the price range. In other words, it will have its largest impact on poor families who buy inexpensive shoes. The costs to consumers will certainly be disproportionately larger than any benefits to workers whose jobs are saved in this very low-wage industry.

As trade disputes go, the shoe case is a peculiar one, for the troubles of the American industry do not basically arise from high costs. Sales of expensive American-made men's business shoes, for example, have held up well. But those models change little from one year to the next. It was in the lines affected by volatile fashions - women's shoes, boots, athletic shoes - that the Americans manufacturers got zapped. Most of these companies are small, isolated, and set in their ways. A few American compnies saw what was happening and quickly moved with their market to the new styles; the current prosperity of those companies strengthens the evidence that it was not cost but taste that swung buyers to the imports over the past decade.

Since this decision was the new administration's first on trade, there will be a great temptation both here and abroad to read it as a signal of future policy. Foreign governments are currently exceedingly fearful - far more fearful, we might say, then the evidence justifies - that this country is swinging toward protectionism. They might usefully remind themselves that, precisely because it was Mr. Carter's first trade case, the symbolisms of American politics did not permit him to turn away the shoemakers with no relief at all.

Along with the rather dubious promises of import restrictions now to be negotiated with Taiwan, South Korea and perhaps other nations, Mr. Carter made a much more useful and hopeful offer. He will help the domestic shoe manufacturers with technical support and, particularly, guidance in marketing. He apparently is willing to make the shoe industry a test of this kind of assistance to help American companies meet the impact of foreign competition. Whatever that adjustment assistance costs, it will be cheap compared with the burden that trade quotas impose on consumers, retail merchants, and the national inflation rate.