4 Visual Thinking in Logic Notebooks and Alba amicorum

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147 Chapter 4 Visual Thinking in Logic Notebooks and Alba amicorum H ow did images in manuscript sources serve as critical tools in the exploration of difficult theories for students, professors, and scholars? And how did the process of artistic creation become a mode of philosophical thinking? In this chapter, I demonstrate that lecture notebooks, as well as contemporaneous alba amicorum, incorporate visual materials as a mode of philosophical thought in itself. I am discussing the visual representations of lecture notebooks and friendship albums in the same chapter, as both these bound manuscript sources functioned as a locus in which students could manipulate visual materials to reflect on philosophical questions in their own voices and with a certain amount of freedom. Furthermore, I aim to show the iconographic overlaps among the prints and drawings found in these sources. To Think through Spatial Constructs The Square of Opposition One frequent diagram in early modern student notebooks that used the space of the page to conceive of logical relationships is the square of opposition, a figure that was first presented in the second-­ century ce text On Interpretation, attributed to Apuleius of Madaura.1 Traditionally, this diagram functioned as an illustration of the logical relations among four different propositions. One of these propositions, known as a universal affirmative, is in the form “Omne X est Y” (Every X is Y). A second, called the universal negative, is in the form “Nullum X est Y” (No X is Y). A third, named the particular affirmative , is in the form “Quidam X est Y” (Some X is Y). The fourth categorical proposition is the particular negative, whose form is “Quidam X non est Y” (Some X is not Y). A print of a square of opposition bound into the 1703 notebook belonging to a Franciscan student at the Grand Couvent named Jouvenet offers a standard example of this diagram (fig. 125).2 Moving clockwise from the upper left corner of this diagram, we find the following four propositions, each in a different form: “Omnis Homo est Justus” (Every man is just), followed by “Nullus Homo Est Justus” (No man is just), and then “Quidam detail of figure 129 148 chapter four Homo non est Justus” (Some man is not just), and “Quidam Homo Est Justus” (Some man is just). The names of the logical relations among these four propositions are marked on lines that connect them to one another. Aristotle outlines the contradictions between the categorical propositions in chapters 6 and 7 of On Interpretation; he also presents the propositions “Every man is just” and “No man is just,” which are used in this 1703 print.3 The term “Contrariae” (contraries) is marked on the line connecting the propositions “Every man is just” and “No man is just”; these propositions are contradictory because it is impossible for both to be true. The word “Contradictoriae” (containing contradictions) appears for the same reason on the diagonal line connecting the propositions “Every man is just” with “Some man is not just,” and “No man is just” with “Some man is just.” The central syllable “Dic” in “Contradictoriae,” in larger print, is encircled at the intersection of the two figure 125 Print of a square of opposition, bound into a notebook by Jouvenet , dated to 1703. 8.9 × 6.7 in. (22.5 × 17 cm). BnF, Département des Manuscrits, Paris [Fonds Latin 18446, fol. 23v]. diagonal lines and their inscriptions. “Dic” is the present active imperative of the verb “to say”; perhaps these three letters serve to emphasize the scholastic notion that propositions were spoken assertions. The term “Subcontrariae” (subcontraries) is written on the line linking the propositions “Some man is just” and “Some man is not just,” because although both these propositions can be true, they cannot both be false. “Subalternae” (subalterns) is inscribed on the line connecting the propositions “Every man is just” and “Some man is just,” because the truth of the universal proposition implies the truth of the particular proposition beneath it. Similarly, the word “Subalternae” is marked onto the line connecting the propositions “No man is just” and “Some man is not just,” because the truth of the universal proposition necessitates the truth of the particular one. The notebook of Brother Georges Couvreux, the student of a teacher named Antoine Mercier, contains an impression of the same print representing the square of opposition that appears in the 1703 notebook by Jouvenet.4 Couvreux’s notebook contains another print depicting three squares of...