described economic processes periphery opposite development core poorer countries impoverished enable countries get richer ref name lastly single society assumption opposes multiple society assumption includes looking world whole ref name world systems theory examined many political theorists sociologists explain reasons rise fall states income inequality social unrest imperialism background immanuel wallerstein developed best known version world systems analysis beginning ref name ph paul halsall http wwwfordhamedu halsall mod wallersteinhtml modern history sourcebook summary
Applied science Business Systems science Systems theory World-systems theory