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Compare mathematics and the political sciences - it's quite striking. In mathematics, in physics, people are concerned with what you say, not with your certification. But in order to speak about social reality, you must have the proper credentials, particularly if you depart from the accepted framework of thinking. Generally speaking, it seems fair to say that the richer the intellectual substance of a field, the less there is a concern for credentials, and the greater is the concern for content. One might even argue that to deal with substantive issues in the ideological disciplines may be a dangerous thing, because these disciplines are not simply concerned with discovering and explaining the facts as they are; rather, they tend to present these facts and interpret them in a manner that conforms to certain ideological requirements, and to become dangerous to established interests if they do not do so.