Political Theory as distinct from Political Science
I found this useful distinction at the University of North Carolina's political science webpage. The final paragraph offers guidelines for drafting arguments, both written and oral.
Political Theory differs from other subfields in Political Science in that it deals primarily with historical and normative, rather than empirical, analysis. In other words, political theorists are less concerned with the scientific measurement of political phenomena than with understanding how important political ideas develop over time. And they are less concerned with evaluating how things are than in debating how they should be. A return to our democracy example will make these distinctions more clear and give you some clues about how to write well in Political Theory.
Earlier, we talked about how to define democracy empirically so that it can be measured and tested in accordance with scientific principles. Political theorists also define democracy, but they use a different standard of measurement. Their definitions of democracy reflect their interest in political ideals--for example, liberty, equality, and citizenship--rather than scientific measurement. So, when writing about democracy from the perspective of a political theorist, you may be asked to make an argument about the proper way to define citizenship in a democratic society. Should citizens of a democratic society be expected to engage in decision-making and administration of government or should they be satisfied with casting votes every couple of years?
In order to substantiate your position on such questions, you will need to pay special attention to two interrelated components of your writing: (1) the logical consistency of your ideas and (2) and the manner in which you use the arguments of other theorists to support your own. First, you need to make sure that your conclusion and all points leading up to it follow from your original premises. If, for example, you argue that democracy is a system of government through which citizens develop their full capacities as human beings, then your notion of citizenship will somehow need to support this broad definition of democracy. A narrow view of citizenship based exclusively or primarily on voting probably will not do. Whatever you argue, however, you will need to be sure to demonstrate in your analysis that you have considered the arguments of other theorists who have written about these issues. In some cases, their arguments will provide support for your own; in others, they will raise criticisms and concerns that you will need to address if you are going to make a convincing case for your point of view.