The two degree limit reflects the dualism of a simplified dose-response relationship. The institutional determinants of risk definition and scientific risk modelling have been traced back to the development of the civil nuclear industry, and the US Atomic Energy Commission's use of probabilistic risk analysis in the 1950s to assess the maximum credible chance of a nuclear reactor accident. The analysis in this chapter assumes that articulating a world view that divides safe from dangerous, impacted from not impacted, can be an act of power which is in fact integral to modern-day politics and science. The setting of environmental limits allows the state to give the appearance of taking action in the face of environmental crisis, and hence maintain its legitimacy. In modern societies political institutions generally make decisions about risk within the framework of cost-benefit analysis (CBA), which seeks to weigh the financial costs of avoiding the modelled risk scenario against the benefits of avoiding the anticipated harm(s).