An opinion about the relative merits of two or more states of the economy that is based on morals or aesthetics rather than logical argument. For example, consider a proposed change which will affect individuals A and B. If each gains a logical argument can be made, based on the concept of a Pareto improvement, in favour of implementing the change. Suppose instead that the change benefits A but harms B. Whether or not it should be made then involves a value judgement on how society should assess the benefit for A against the harm to B. The presence of value judgements is a defining feature of normative economics, and their absence a characteristic of positive economics.