Having a political ideology

Explain what it means to have a political ideology, and how ideology is distinct from party identification. Then, discuss the motives for adopting an ideology (not specific ideologies, but any ideology in general). In 1964, Philip Converse published a study of political attitudes, in which he claimed that very few people were ideological. Do you think things have changed since then? What are the reasons for changes or the lack of them? Is party identification or ideology a larger determinant of people's political attitudes?