Criticism of socialism refers to any critique of socialist models of economic organization and their feasibility; as well as the political and social implications of adopting such a system. Some criticisms are not directed toward socialism as a system, but are directed toward the socialist movement, socialist political parties or existing socialist states. Some critics consider socialism to be a purely theoretical concept that should be criticized on theoretical grounds (such as in the Socialist calculation debate); others hold that certain historical examples exist and that they can be criticized on practical grounds.