Chapter 3: Contradictions
The history of ideas generally assumes an underlying coherence to the discursive materials it analyses, seeking to reduce internal contradictions and dissonances to mere defects or mistakes and thereby revealing a deeper level of unity. This is both a prerequisite to research in the history of ideas and an end-product of that research. There are, however, multiple kinds of unities to which the historian of ideas appeals; these range from ideal, logical systems to more poetic, thematic unities based in common culture or individual psychology. For this method, 'contradiction is the illusion of a unity that hides itself or is hidden.' The history of ideas sometimes comes to the opposite conclusion as well: contradiction and difference are in fact the very principle of discourse itself, driving it into being. This position is still, however, a reduction of complex systems of contradiction to a single principle of contradiction that underlies all discourse. Thus, for the history of ideas, 'to analyze discourse is to hide and reveal contradictions.'
Archeological analysis, on the other hand, takes contradictions neither as illusion nor as deep principle but as 'objects to be described' in their specificity. Archeology measures 'the extent and form of the gap' that separates two statements or discursive formations; in short it describes 'spaces of dissension.' Archeological analysis is generally not interested in contradictions that result from opposing descriptions of the same object in the same enunciative mode. Instead, it is concerned with 'intrinsic oppositions,' in which the contradiction stems from the clash of enunciative sub-fields within a discourse (i.e., from two different 'ways of forming statements'). Intrinsic oppositions are not blunt facts, but must be described in detail, with attention to the specific type, level, and function (within a given discourse) of the opposition in question.
Chapter 4: The Comparative Facts
Archeological analysis proceeds partly by comparison between statements or whole discourses, although it describes a wide range of different kinds of separations and relations. This mode of comparison itself differs significantly from that used in the history of ideas. First of all, archeological comparison is always 'limited and regional,' seeking to describe the relations between a set of statements or discourses rather than taking that set to represent variations on a more general background (such as 'the totality of contemporary discourses'). Thus, 'archeological comparison does not have a unifying, but a diversifying, effect.'
Secondly, and for the same reasons, archeological analysis excludes certain kinds of comparisons that seek identity across different discursive formations (comparisons, for example, that ask what categories Turgot used both in his analysis of coinage and in his theory of language). Archeology can describe 'isomorphisms' between discourses, but only at the level of the enunciative field (rather than ideas, knowledge, or experience). When it does describe such isomorphisms, it does so in detail, with attention to slight re- arrangements of enunciative rules. With this method, isomorphisms can be found in radically different discourses, and radical differences can be found between two uses of a single word.