Goods which it is difficult or impossible to exclude the public from using, and where the use by one does not exclude the use by others. The atmosphere or the sun’s energy are naturally occurring public goods. A defence system, the rule of law, and a democratic system of government are public goods. It is controversial to what extent government has the right to impose taxation in order to create other public goods, such as old age pensions, the health system, or education. Public goods that do not occur naturally cannot be easily provided without compulsory taxation, since everyone has a motive to be a free rider.