Few topics in Political Science appear as burdened with difficulties as the term "ideology". Intra-individual connections between beliefs and ideas are however not sufficient for the existence of correlations between ideas or attitudes in the general public, which poses a problem for the operationalization of constraint in terms of correlations. There is evidence of systematic differences between individuals in terms of belief system constraint, at least if measured in terms of correlations among attitudes. Those correlations are however inter-individual patterns, while constraint really is a concept that concerns intra-individual patterns of attitudes. The idea of ideological distinctions as inferential devices is not restricted to research motivated by the spatial theory of voting. If voters do not care for each and every implication that an ideology has, then a complete and coherent belief system may not be necessary for ideological cues to be useful for them.