Hegel noted disparagingly in his Wissenschaft der Logik how most of the earlier books on logic did nothing to justify why a certain ordering was followed, but merely started with concepts, continued to judgements and so on. Indeed, the traditional books on logic – and Wolff's logical works are no exception – followed closely the order of Aristotelian Organon: first, Categories, a book classifying the basic concepts, then, On interpretation, a book telling how to combine concepts into statements or judgements, Prior analytics, a book telling how one could use syllogisms to deduce judgements from previously known judgements, and finally, Posterior analytics, a book applying syllogistic to scientific methodology.
I already remarked in the previous text how peculiar the inclusion and even the centrality of methodology might be to a modern reader, who is used to logic as a study of certain formal languages and at most a canon of reasoning. Furthermore, the order followed would be strange to this reader, because the order of the modern truncated logic is in a sense reversed, when the propositional logic already deals with deductions and only the more complex predicate logic introduces the more fine-grained structure of the propositions.
But perhaps most alien to the modern notion of logic is the doctrine of concepts. In Aristotle's Organon, Categories has a clear ontological import, as it e.g. defines individual substances as the primary entities. Modern formal logic, on the contrary, has become more and more removed from any ontological presuppositions. Thus, when Russell stated in Principia mathematica that logic presupposes the existence of at least one entity, modern free logic remains valid even if there should be nothing at all. This is perhaps the ultimate in deontologisation of logic, which strives to be an ontologically neutral science.
Wolff's theory of concepts is not so much an ontological, but a psychological study, which might be even more of a blasphemy to the modern logic that began with the Fregean critique of psychologism. Yet, Wolff is not alone in this, but instead almost all logicians of the time defined concepts in psychological terms – or at least this is what Hegel accuses them of doing. I shall leave the discussion of Wolff's theory of concepts to the next time, but for now I wish to speak of two mental capacities that lie on the basis of concepts in Wolff's account, that is, Empfinden, which we might translate here as perceiving, and Gedancken or thinking.
The reason why I want to discuss these two terms is Kant's analysis of where his predecessors went wrong when they discussed human theoretical faculties. Kant roughly divided the previous philosophers into two camps. The followers of Locke emphasised the status of perceptions, and indeed, Kant suggests, tried to make thoughts into a sort of perceptions. The followers of Leibniz, on the other hand, tried to do just the opposite, that is, they tried to intellectualise all appearances. Both sides erred, says Kant, because thoughts and perceptions or concepts and intuitions are two very different processes.
Wolff is usually seen as a follower of Leibniz, so one would assume Kant would count him as one of the intellectualisers. And indeed, Wolff boldly states that perceptions are a species of thoughts. But here we have a good example of philosopher's speaking right past each other. Two botanists won't probably have any difficulty to understand one another, when they both speak of potatoes, but mixing concepts of two philosophers is bound to produce confusion.
We shall have to decide later on – in about decade or so – what Kant meant by concepts and intuitions, but now is the time to define Wolffian terminology. Those who know German have most likely been raising objections in their mind to me translating Empfinden as perceiving. But Wolff's definition of the term is so broad that perception appears to me a more suitable translation in this context than e.g. sensation. We perceive something, Wolff says, when we are conscious (bewusst) of it as being present to us. Although Wolff's actual examples then consist of mere sensations like pain or light, the definition itself could also apply to an awareness of e.g. a red ball or a sugar cube.
Now, the link to consciousness is the important element in Wolff's definition, because through consciousness Wolff also defines thoughts. Thoughts, for Wolff, are effects of the soul, by which we are conscious of ourselves. Wolff does not clearly state why perceptions then would be thoughts, but the connection seems clear and goes back to Descartes. When we are conscious of something, we at the same time must be conscious that we are conscious and thus we must be conscious of ourselves. In other words, consciousness presupposes self-consciousness. With these particular definitions Wolff must arrive at the conclusion that perceptions are also thoughts. Indeed, the connection of the two terms in their Wolffian meaning is so natural that it does not imply any intellectualisation of perceptions that Kant is worried about.
That's all for now. Next time we shall see how perfect Wolff's concepts are when compared with the concepts of his competitors.