Definition and Essence

Many medieval Aristotelians were engaged in the essentialist project of reducing modal, classificatory, and scientific truths to true claims about the essence of objects. The success of this project requires a semantically precise account of what one is committed to in making these essence-claims. Many also treated the attribution of a genus-differentia definition (GDD) to an object as a paradigmatic type of essence-claim. What is the scope of GDD-attribution? When is a GDD-attribution true? In this paper, I examine Robert Kilwardby's answers to these questions in the context of his metaphysics and semantics. Though Kilwardby defends the traditional position that only substances have a definition, he seemingly inconsistently applies GDD to characterise the essences of many non-substantial objects, including the syllogism. I vindicate Kilwardby's consistent and broad employment of GDD by showing that and how successful GDD-attribution reveals the metaphysical constitution of the object defined. Kilwardby argues that by considering non-substantial objects, e.g. triangle, apart from their modifying a substance, we may consider them to have essences and essential forms. I then show how successful GDD signifies the constitution and ordering of these forms within any object's complete essential form. I illustrate Kilwardby's analysis by showing how he understands the GDD-attribution: 'man is a rational sensible mortal body'. I thus advance our understanding of how a foundational component of the medieval essentialist project works. 

Gottfried Wilhelm Leibniz (1646–1716) stands as a towering polymathic mind in the history of philosophy, celebrated for his multifaceted contributions that encompass metaphysics, epistemology, mathematics, and much more. Among his diverse philosophical endeavors, the concept of the general science (scientia generalis) has emerged as a subject of significant interest. In Leibniz's expansive vision, the general science is "nothing else than the science of thinking [...], which is not only a logic [...] but also an art of invention and a method of ordering knowledge, a synthesis and analysis, didactics and a science of teaching" (Couturat 1903: 511). Closely related to Leibniz's general science is the concept of the universal characteristic (characteristica universalis). It is envisioned as a universal language or symbolic system, a language of thought and "the art of forming and arranging the characters in such a way that they agree with the thoughts, i.e. so that they have amongst them the same relation that subsists amongst thoughts" (Leibniz, cited in Mugnai 2018: 178).
Despite the prominence of the general science and the universal characteristic in Leibniz's writings, the relationship between the two remains a subject of debate. While scholars generally acknowledge the close interconnection of these concepts (Burkhardt 1987, Gensini 1992, Pelletier 2018), there is a sense of mystery surrounding the linguistic influence of the universal characteristic within the general science. Therefore, this presentation seeks to elucidate the relationship between Leibniz's universal characteristic and the general science and offer a novel aspect of interpretation about general science's linguistic dimension. 
By delving into the linguistic dimensions of Leibniz's thought, we shed light on the processes by which ideas are formulated, communicated, and advanced within the general science. Leibniz himself expressed a profound interest in the idea of a universal language that could serve as a means of precise communication among thinkers of diverse backgrounds. His aspiration for the universal characteristic to constitute such a language prompts us to reevaluate the fundamental nature of general science.
In this exploration, we navigate the intricate terrain of Leibniz's philosophy, scrutinizing the intersections of language, thought, and scientific methodology. By engaging with Leibniz's insights on the linguistic dimension of general science, we not only deepen our understanding of his philosophical legacy but also contribute to ongoing debates concerning the role of language in scientific inquiry, the nature of scientific representation, and the methodology of scientific thought.






References


Burkhardt, H. 1987. The Leibnizian characteristica universalis as link between grammar and logic. In: Speculative grammar, Universal Grammar, Philosophical Analysis, ed. Buzzetti, D., Ferriani, M. Amsterdam: John Benjamins Publishing Company, 43–64.
Couturat, L. 1903. Opuscules et fragments inédits de Leibniz. Paris: Felix Alcan.
Gensini, S. 1992. « Filum meditandi »: Semiotics and Scientific Knowledge in the thought of G. W. Leibniz. In: Histoire Épistémologie Langage 14(2): 107–127. 
Mugnai, M. 2018. Ars characteristica, logical calculus, and natural languages. In: The Oxford Handbook of Leibniz, ed. M. R. Antognazza, 177-207.
Pelletier, A. 2018. Scientia generalis and encyclopedia. In: The Oxford Handbook of Leibniz, ed. Antognazza, M. R. New York: Oxford University Press, 162–176.

Leibniz put forward a theory of truth surprisingly close to Hobbes's, the conceptual containment theory: a categoric proposition, A is B, is true if and only if the concept of the predicate, B is 'contained' in the concept of the subject (LA 56, DM 13). This definition reverses the proposal that Hobbes had given in De Corpore, that a proposition is true iff the concept of the subject is contained in the concept of the predicate (OL I 31). Leibniz's definition is intensional while Hobbes's was extensional, but they seem to agree that truth is in the conceptual subject-object relation, and does not refer to extraconceptual reality.
Yet since even before Leibniz had formulated his conceptual containment view, he had insistently been attempting to refute the 'arbitrariness of truth' in Hobbes's "plus-quam-nomialism", "because truth allegedly depends on the definition of terms, and definitions depend on the human will." (A VI ii 428). Scholarship has recognised that Leibniz's reaction is more sophisticated than the standard (AT 178/79; Arnauld & Nicole p.68) response to Hobbes. That is because Leibniz recognised that for Hobbes words are both signs of thoughts and names of things (EW i, 17; EW, 18 iii, 25).
But the root of Leibniz's rejection of Hobbes's truth theory has gone unrecognised. In Hobbes's materialism, the relationship between the thing which the word names and the thought which it signifies is a purely causal one (AT 168). But this is the destruction of what we would today call intentionality: the thoughts are not about the things, but merely occur because of them, and thus they cannot be said to correspond to reality as needed (NE 397). Various commentaries have recognised that Leibniz aims for intentionality through a language invariant structural analogy between thought and reality (L 184; G, vii, 219). This is because "… ideas are in God from all eternity, and they are in us, too, before we actually think of them." (NE 300). But the ideas in question here are the possibilities of individuals, not of universals (NE 323).
What recent commentaries have overlooked is that this explains why Leibniz needs to move from the extensional to the intensional definition of truth. Leibniz is a (sui generis) nominalist (LA 101), thus, if truth depended on containment in the predicates (universals), the definition would be only nominal. Instead, by placing all predicates in their subjects, the God given idea which enables the thought of the concept is isomorphic to what is real, namely individual substances.
Therefore the ultimate basis for Leibniz's rejection of Hobbes' theory of arbitrary truth is not just that 'truth is in things, not words'. More in depth, it is that Hobbes's theory leaves no room for a representation of things within us which is proportional to reality, and the reality-thought relationship is only causal. Leibniz's shift to intensionality was thus motivated by the goal of saving the veracity of intentionality.