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No one has mentioned the fact that Manjoo amply lays out all his sources with connecting links (he even warns you when the file is huge) so that you can verify his sources, and at the same time Kennedy does no such thing. More to the point, Manjoo points out mitigating facts that Kennedy conveniently leaves out of his analysis--from the very studies that Kennedy reports as authoritative. That right there calls into question Kennedy's credibility: selective use of facts with no easy opportunity for the reader to check up on him.
Thanks Manjoo, for your diligent work in calling Kennedy's bluff.