I have just picked up Paul Johnson's Intellectuals: From Marx and Tolstoy to Sartre and Chomsky, and am delighted with the introductory paragraphs:
Over the past two hundred years the influence of intellectuals has grown steadily. Indeed, the rise of the secular intellectual has been a key factor in shaping the modern world. Seen against the long perspective of history it is in many ways a new phenomenon. It is true that in the earlier incarnations as priests, scribes and soothsayers, intellectuals have laid claim to guide society from the very beginning. But as guardians of hieratic cultures, whether primitive or sophisticated, their moral and ideological innovations were limited by the canons of external authority and by the inheritance of tradition. They were not, and could not be, free spirits, adventurers of the mind.
With the decline of clerical power in the eighteenth century, a new kind of mentor emerged to fill the vacuum and capture the ear of society. The secular intellectual might be deist, sceptic or atheist. But he was just as ready as any pontiff or presbyter to tell mankind how to conduct its affairs. He proclaimed, from the start, a special devotion to the interests of humanity and an evangelical duty to advance them by his teaching. He brought to this self-appointed task a far more radical approach than his clerical predecessors. He felt himself bound by no corpus of revealed religion. The collective wisdom of the past, the legacy of tradition, the prescriptive code of ancestral experience existed to be selectively followed or wholly rejected entirely as his own good sense might decide. For the first time in human history, and with growing confidence and audacity, men arose to assert that they could diagnose the ills of society and cure them with their own unaided intellect: more, that they could devise formulae whereby not merely the structure of society but the fundamental habits of human beings could be transformed for the better. Unlike their sacerdotal predecessors, they were not servants and interpreters of the gods but substitutes. Their hero was Prometheus, who stole the celestial fire and brought it to earth.
One of the most marked characteristics of the new secular intellectuals was the relish with which they subjected religion and its protagonists to critical scrutiny. How far had they benefited or harmed humanity, these great systems of faith? To what extent had these popes and pastors lived up to their precepts, of purity and truthfulness, of charity and benevolence? The verdicts pronounced on both churches and clergy were harsh. Now, after two centuries during which the influence of religion has continued to decline, and secular intellectuals have played an ever-growing role in shaping our attitudes and institutions, it is time to examine their record, both public and personal. In particular, I want to focus on the moral and judgmental credential s of intellectuals to tell mankind how to conduct itself. How did they run their own lives? With what degree of rectitude did they behave to family, friends and associates? Were they just in their sexual and financial dealings? Did they tell, and write, the truth? And how have their own systems stood up to the test of time and praxis?