“One of the leading themes of current philosophy is that the notion of objectivity is utterly illusory. This is not some post-modern pose: the subjectivity of scientific knowledge has been proved with mathematical rigour. The upshot of these proofs is that data merely serves to update our pre-existing beliefs, and that its impact on those beliefs depends on such touchy-feely concepts as trust. There was a time when philosophers would have been content to point all this out, and then sit back with a smug smile. No longer…”