Risk is one of the most interdisciplinary subject-areas studied by scholars and scientists. A large number of disciplines provide general perspectives on risk. Major such disciplines are statistics, psychology, decision theory, philosophy, economics and sociology. In addition, an even larger number of disciplines investigate specific risks. Biologists study environmental risks, climatologists weather-related risks, medical scientists health risks, engineers technological risks, etc. This chapter argues against reductive approaches that attempt to reduce this multiplicity of interacting perspectives. The most influential such reductive approach is risk-benefit analysis, which is based on the assumption that everything that has to be taken into account in risky decisions can be treated as equivalent to the gain or loss of a sum of money. It is argued that an accurate understanding of risk requires insights from many disciplines, and in particular that normative approaches such as ethical risk analysis are indispensable.