I have studied Wolff's idea of imagination in an earlier post quite extensively, but I still feel there's some possibility for clarifying the role of this faculty in more detail. Especially I shall have to emphasise its role as still officially one of the lower faculties, but even so, on a higher level than mere sensation as such.
Imagination, then, is supposed to be the faculty that reproduces ideas of certain individuals, even if they are absent. The reproduced ideas created by imagination Wolff calls phantasms. They are thus to be distinguished from sensuous ideas, which could not be produced without the presence of some concrete thing corresponding to these ideas. Still, there could be no phantasms without any sensations. That is, Wolff ascribes to Lockean principle that mind without experience would be like a blank slate without anything written on it.
I have already noted about the similarity of Wolffian distinction between sensations and phantasms and Humean distinction between impressions and ideas. Like Hume, Wolff also notes that phantasms or products of imagination are less vivid and have fewer details. Then again, this is actually positive according to Wolff and speaks in favour of phantasms. The vividness of sensations makes it difficult to concentrate on them: if we try to look at a beautiful painting, a sudden honk from car horns outside the window can ruin our aesthetic experience. The lack of unnecessary details in phantasms, on the other hand, helps to make them clearer, which is a requirement e.g. for mathematical thinking. True, phantasms can also be confused by sensations, and a honking car horn will make it difficult to follow mathematical constructions imagined in your head. Yet, even this obstacle can be circumvented, as soon as one finds a dark room isolated from all external stimuli.
The lack of sensations thus helps us to concentrate on our phantasms. Indeed, when all sensations have been cut out, phantasms become more vivid, which explains, according to Wolff, the seeming substantiality of our dreams. Like all experiences, dreams come with different levels of clarity, starting from a completely dreamless sleep and ending with lucid dreams, in which we are aware that we are dreaming.
Imagination as a faculty of producing phantasms is thus important for its own sake, but it also provides materials for other faculties, Wolff continues. Firstly, phantasms are more in our control than sensations are. In fact, a given phantasm can be, as it were, divided into its constituent phantasms – we can imagine a human head, independently of its body. Furthermore, we can also combine different phantasms, attaching a human head onto a body of a horse, thus creating the phantasm of a centaur. This is the work of what Wolff calls inventive faculty, which is responsible, among other things, all the works of fiction.
Secondly, we can use phantasms as indicators for something we have sensed or in general experienced at some past point of time. This is the task of memory, which Wolff clearly says not to be any container of images or memories. Instead, memory is actually a name common to various interacting faculties, which, for instance, recognise a sensation or phantasm as resembling something that we have witnessed, or produce phantasms of things we have witnessed.
Imagination, together with its related faculties, forms then a second level in the hierarchy of faculties in Wolffian psychology of cognition. Together with sensation, they form the lower level of cognition, in which imagination appears clearer than the multifarious and uncontrollable sensations. This does not mean that sensations could not be basis of clear and even distinct experiences, as becomes clear in the next post, where I will move to consider the higher levels of cognition.