Christian Wolff (1679-1754)
Kant stated in the Preface to the second edition of the Critique that Wolff had precribed the correct method for metaphysics: "orderly establishment of principles, clear determination of concepts, insistence upon strictness of proof, and avoidance of venturesome, non-consecutive steps in our inferences" (Bxxxvii). But though methodologically sound, Wolff had neglected to prepare the ground for his demonstrations by undertaking a critique of the organ of metaphysics, pure reason. In particular, he treated sensibility as "nothing but a confused representation of things, containing only what belongs to them in themselves, but doing so under an aggregation of characters and partial representations that we do not consciously distinguish" (A43/B60). In treating the difference between sensibility and understanding as merely "logical," Wolff (along with Leibniz) "has given a completely wrong direction to all investigations into the nature and origin of our cognition" (A44/B61).
Ontology is the study of "beings" or "entities." A being is whatever can be thought without contradiction. For example, a triangle is a being, since there is no contradiction in thinking three straight lines, each of which shares an endpoint with another. A more specific being is an equilateral triangle. (A triangular circle, on the other hand, is not a being.)
A being has a number of qualities called "essentials." The essentials must be compatible with each other are primitive, in the sense that they are not the consequence of anything else. The essentials of a triangle are the qualities of having three straight lines and having the lines joined at the endpoints.
There are other qualities of a being which are not essentials but are derived from them. These are called "attributes." An equilateral triangle has the essentials of a triangle plus the quality of having its sides of equal length. An attribute of such a triangle is the quality of having three equal angles. This quality follows directly from the essentials but is not, on Wolff's view, an essential itself.
A third kind of quality is a mode. Modes are quite different from both essentials and attributes, in that they are dependent on other beings. While the essentials make modes possible, their actuality depends on the relation of the being to another being or beings.
Existence or actuality is the full determination of a being, the "completion of possibility." The essentials of a thing make many modes possible. An equilateral triangle, as a possibility, is undetermined as to the length of its sides, for example. The filling out of the undetermined mode is the actualization of a thing. Contrary to our current notion of ontology (the study of "what there is"), Wolffian ontology is silent with respect to which things exist and which do not exist. It is left for special metaphysics to settle these matters.
The existence of a being may be necessary or contingent. A necessary being is one which has no modes, i.e., all of whose qualities are either essentials or attributes. Its qualities are therefore completely determined by itself. A contingent being is one which has modes and hence depends on some other being for the completion of the set of its qualities. Metaphysics will show that ultimately the line of dependence must come to an end with a necessary being.
