Knowledge filters group problems based on our level of knowledge of cause and effect. If we know little about the causes, scope or effects of a problem, the do no harm principle suggests that we should be cautious about adopting solutions. Risk filters group problems based on the degree of risk they pose. If the risk to health or safety is high, then the flexibility and balancing principles indicate a strong case for strict regulation. If the risk is low, the flexibility and balancing principles suggest that government's role should be limited to setting standards that firms can meet in the least costly ways.
Strategy filters partition problems based on the potential for different types of solutions.
For example, we might reduce a pollutant through regulation, use of the tort system, imposition of taxes or fines or the creation of tradable property rights. Once we have identified the potential strategies, we could employ the balancing and flexibility principles to choose among them. Ownership filters partition problems based on the degree to which property rights are defined and protected. If resources are owned, using the individualism and compensation principles can improve social well-being by clarifying and enforcing responsibilities for environmental wrongs and by rewarding individuals who enhance environmental quality. Where resources are unowned or property rights are not well-defined, other filters and principles are applicable.