JEAN-BERTRAND ARISTIDE is not a democrat to his fingertips. But he is the democratically elected president of Haiti. If future generations of Haitian politicians are to be true democrats, committed to the rule of law and to genuinely democratic institutions and procedures, Mr. Aristide must be restored to the presidency from which he was ousted by a military coup Sept. 30.According to a delegation from the Organization of American States that visited Haiti last weekend, Aristide is deeply resented and feared not only by the military but also by political opponents and a large segment of the business class. The fear stems in part from Aristide's reckless inciting of class hatreds and seeming willingness to countenance mob justice by his impoverished followers. Since his inauguration in February, Aristide has also been less than punctilious in observing Haiti's constitution. Still, Aristide was elected overwhelmingly in balloting adjudged free and fair by OAS and other international observers. Neither his ouster nor the Haitian parliament's subsequent designation, at gunpoint, of an interim president have constitutional foundation. The OAS and the United States are right to insist on Aristide's return to office and to back up their demands with sanctions. It's clear, however, that Haiti's strife will not end if Aristide is simply permitted to get back to business as usual. His return must occur in the context of an agreement that, though far from leaving him as a figurehead president, sets some ground rules for his exercise of constitutional powers. These must include a pledge by Aristide to do all he can to direct his faithful legions away from "God's justice," a code term for vigilante bloodshed. Lynchings are likely to continue, though, until a functioning system of justice is created in Haiti. The OAS, the US, or France could provide aid and expertise to strengthen the judicial system. Haiti is a nascent democracy, emerging from two centuries of repression. It cannot be held to the same standards of political conduct as mature democracies. But it must be held to the most fundamental standard, which is that political legitimacy does not come from the barrel of a gun.