The recent proliferation of new data and technologies enables increasingly finer personalization of products and prices in every domain. In insurance, this revives and enlarges old debates around fairness that have never been completely settled. We will argue that the commonly accepted “actuarial fairness” as based on the “individual cost of risk” derives in fact from a conflation: while it indicates the average cost for a group of insureds from the perspective of an insurance company—and is therefore sound from a (...) business profitability viewpoint—it is arguable whether it represents the “fair price” for the individual insured. We first show in a historical perspective the intertwinement of conceptions of fairness with knowledge, in order to point to the alternative to actuarial fairness for insurance. We then describe the intrinsic difference between the insured and the insurer when underwriting an insurance contract. Finally, we build on this distinction to discuss the meaning of fairness in insurance prices. We thus hope to re-center the debate around insurance fairness on its underlying solidarity mechanisms rather than technical and actuarial considerations. (shrink)