Wolff defines logic as the discipline for guiding cognition to truth. That is, for Wolff logic is not just a canon or rule book for separating clear falsities from possible truths, but an organon or methodology for finding truths. Now, Wolff notes that such a discipline or science should properly be called an artificial logic and distinguishes it from what he calls natural logic. Such a natural logic might be an innate capacity for searching truths, but it might also be learned through education, like rules of thumb for solving some mathematical problems, just as long as we are still unclear about why such rules actually work.
Natural logic means for Wolff then just the usual workings of cognition, and its proper place of discussion would be psychology, on which logic then depends on. Natural logic forms in Wolff a process, stages of which are familiar already from Wolff's German writings and in which we begin with sensations or perceptions (as I've noticed before, Wolff does not distinguish these carefully). Some of the sensations are somehow connected to things that are external to the consciousness and that appear to make impressions on sense organs. Yet, Wolff also admits the existence of an inner sense, by which we come to know ourselves.
The sensations or perceptions form then the starting point of cognition for Wolff, although they are also its most rudimentary phase. While perceptions can only refer to things that are actually present, imagination helps us to e.g. recollect images of absent things that we have seen previously. Both perceived and imagined things can then be concentrated on and apprehended. Such an act of apprehension requires that we use the perception or the imagination as a representation of the real thing.
Suffice to say, this representation is what Wolff called in German Begriff (a concept), while in Latin version he uses words like Notio and Idea, which reveals the clear Lockean influences. While Kant was later to disparage Wolff for intellectualising appearances, he was actually doing quite the opposite and made at least some concepts into mental pictures. Thus, the image of the rose in front of me or of the one I remember seeing are all concepts for Wolff. True, we can also refer to these images and individuals represented with them by words, but this is secondary. Note that all the concepts at this point concern only individuals, since universalities cannot be perceived or imagined as such.
The mental images of past and present things can then be compared with one another. These comparisons might immediately instigate in us an awareness of e.g. certain similarities between different things. This awareness is the first instance of judgements, and like concepts, they have their own linguistic counterpart in propositions. Furthermore, it is through such judgements that universal concepts come to existence – when we think of whiteness and if we are not just thinking about the word ”white”, we must be thinking about several white things and the recognition of their similarity.
From judgements of similitude we form then notions of genera of things, which are nothing apart from the things and their similitude and the words we use for designating these spurious entities – we thus see Wolff here advocating nominalism. In addition to similarities, we also intuitively note dissimilarities between things and can thus divide genera into different species. Finally, we can extend the set of true judgements we can make by using our intuitive judgements as a basis on which we can build complex demonstrations.
Now, if all of this is natural logic, what task is then left for artificial logic anymore? That is, if one can do all this by instinct or at least learn it by following how others use their reason, why should we need an independent science of reasoning? Wolff himself doesn't consider the problem, but Hegel will have a convincing answer in an analogy. Surely our digestion, muscles etc. work by themselves, but we can still profit from learning anatomy and physiology, because we can then eat in a healthy manner, exercise properly etc. Similarly, we surely do think naturally, but logic teaches us how to think well.
Next time I shall say something about Wolff's classification of concepts.