All historical inquiries start from relics from the past that are available to us in the present. Historians have before them a collection of source material consisting of books, newspapers, works of art, government reports, census data, and other such things. Because this source material comes from the past, it can provide evidence of the nature of the past. None the less, because it is not itself the past, historians use it to postulate historical objects; they tease out its secrets in an interpretative process. To postulate any one historical object, however, historians also have to postulate other such objects and to relate them to one another in a narrative structure. Historians of ideas, of course, concern themselves exclusively with ideas. They look only at what relics from the past tell us about historical meanings, not what they tell us about other historical objects. Like all historians, however, they use relics from the past to devise narratives that relate various historical objects to one another. The logic of the history of ideas concerns the forms of reasoning historians ought to use to do this. It examines the forms of justification and explanation appropriate to the discipline: it examines, first, the way historians should defend the narratives they tell, and, second, the way they should relate the objects they postulate to one another in a narrative.

Clearly a logic of the history of ideas must apply to itself.