To the Editor: Jack Carter (6/3) explains how 25% of registered voters (plus one) could pass a measure under the Double Majority rule, concluding that the rule is not unfair. But if say 40% of registered voters voted in favor of the same measure, while fewer than 50% of registered voters turn out, the measure would fail! How is it that MORE people (than in his example) could vote FOR a measure and fewer AGAINST it, and have it fail? There are many sad cases. On May 16 the Pleasant Home school local option failed with 56% voting in favor, but shy by 55 votes of 2071 needed to validate the election. Even if the 55 needed votes were all NO votes, the measure would have then passed! Is this fair? If people want to defeat a measure of any kind they should have to vote against it plain and simple. John Miller Southwest Portland