BARELY THREE WEEKS have passed since Rep. John Anderson announced his intention to explore whether the ways and means were available to him for running as an independent presidential candidate. The early returns are certainly anything but discouraging to Mr. Anderson and his fans.

As we have already noted, many states have laws whose single purpose seems to be to limit their voters' presidential choices to the nominees of the Democratic and Republican parties. Since virtually all the people involved in enacting these statutes are either Democrats or Republicans, the restrictive features should not surprise anyone. In the four states that have had filing deadlines in the past three weeks, nonetheless, the Anderson campaign has met the filing requirements.

In addition, the most recent Harris poll has to give Mr. Anderson a boost as he and his supporters go about the arduous task of meeting the requirements elsewhere. In his national survey, Mr. Harris found former California governor Ronald Reagan the first choice of 38 percent of the voters, President Carter the choice of 33 percent, and Rep. Anderson the choice of 23 percent. When the voters interviewed were offered the hypothetical choice, with Mr. Anderson given a serious chance of winning, the Anderson share jumped to 29 percent.

There are other encouraging figures in the Anderson picture in addition to survey results. In the past three weeks, according to the Anderson campaign, some $900,000 has been raised for the independent candidacy. The abiity to raise adequate funds is something that can make any candidate in our politics "serious."

President Carter's campaign leadership has already announced its intention of challenging the Anderson efforts for ballot listing wherever it is thought he can be prevented from being listed. For now at least, Mr. Reagan's supporters seem content to watch while Mr. Anderson goes about filing in the different states and Mr. Carter's agents try to upset the filings.

There are still 5 1/2 months to go until Election Day. In the past, independent candidates have looked much stronger on Labor Day than on Halloween. But there is little question that the one-word answer from the Anderson exploratory effort will be: go.