Kristol played a crucial role in the development of the modern conservative movement. More on this later. Condolences to his family, which includes Ashbrook Board Member William Kristol. AEI's obituary is here.
UPDATE: NY Times obituary is here. Some lines:
Yet underlying the invective was an innate skepticism, even a quality of moderation and self-mockery, which was often belied by his single-mindedness. This stalwart defender of free enterprise could manage only two cheers for capitalism. "Extremism in defense of liberty," he declared, taking issue with Barry Goldwater, "is always a vice because extremism is but another name for fanaticism." And the two major intellectual influences on him, he said, were Lionel Trilling, "a skeptical liberal," and Leo Strauss, "a skeptical conservative."