Investigations in the sociology of knowledge usually take as their point of departure some substantive property of a mode of thought. They then seek to delineate and understand the social origins of that mode of thought. This paper suggests the possibility of supplementing the substantive approach with structural materials. Portions of two different intellectual systems are treated empirically to ascertain the manner in which their demonstrations of proof are structured. These structures are uncovered through the use of Guttman scale analysis. While any set of branching deductions may be considered a partly ordered set, the findings reported here show that the portions of the intellectual system chosen for analysis converge to an almost perfectly ordered set (a Guttman scale). Finally, known properties of Guttman scales are assigned to the structural dimension, and implications for the sociology of knowledge are drawn.