Econ chapter 17 notes and terms public goods and common. People can be excluded from consuming them and the extent to which one person"s consumption rivals the consumption of others. Excludable a good is excludable if it is possible to prevent someone from enjoy its benefits: a good is non-excludable if it is impossible (or extremely costly) to prevent anyone from benefiting from it. Rival a good is rival is one person"s use of it decreases the quantity available for someone else: a good is non-rival is one person"s use of it does not decrease the quantity available for someone else. Private goods both rival and excludable. (ex. Can be consumed simultaneously by everyone, and nobody can be excluded from enjoy its benefits. (ex. A unit of a common resource can be used only once, but nobody can be prevent from using what is available. (ex.