There is a widespread recognition of a 'crisis' in official scientific expertise, related to the increase of 'uncertainty' and the loss of 'trust', and whose cure is believed to lie in 'participation'. I argue that the crisis results from structural features of the globalising knowledge economy, and the contradictory roles of governments, acting both as promoters of global business enterprise and also as regulators on behalf of a sophisticated and suspicious public. I explain the crisis by substituting 'safety' for 'risk' as the operative concept, and also using 'paradox' as an explanatory tool. I produce a closed-cycle paradox, analogous to the classic Catch-22, to exhibit the contradictions in the situation. I discuss ways of resolving these, which include the recognition of policy-critical ignorance and the adoption of the perspective of post-normal science.