So analytics isolates understanding and its forms of operation as the object of study, just like transcendental aesthetics isolated sensation. But what is understanding? In Kant’s words:

‘Independently of sensibility, we cannot possibly have any intuition; consequently, the understanding is no faculty of intuition. But besides intuition there is no other mode of cognition, exept through conceptions; consequently, the cognition of every, at least of every human, understanding is a cognition through conceptions – not intuitive, but discoursive. All intuitions, as sensuous, depend on affections; conceptions, therefore, upon functions. By the word function I understand the unity of the act of arranging diverse representations under one common representation. Conceptions, then, are based on the spontaneity of thought, as sensuous intuitions are on the receptivity of impressions.’ (CPR, p.72)

Understanding is also defined as the faculty of judging, where by judgement Kant means the mediate cognition of an object, the representation of a representation of it, which funtions as unifying our representations of objects under higher representations. In other words, the function of understanding is to order the multiple under a common representation. In transcendental logic, the multiple to be unified is only the pure multiple of pure intuition (space and time). The unifying activity of understanding produces synthesis. In his words, synthesis is the activity of conjunction (whether conscious of unconscious, be it of the manifold in intuition, sensuous or non-sensuous, or of several conceptions), which is an act of the understanding and originates only in the subject. Without the subject conjuntion cannot be given through objects, and synthesis is ‘an act [of the subject’s] purely spontaneous activity/ (93). The different modes through which understanding synthesises are called categories (or pure concepts). Here again, Kant refers to the etymological root of aristotelian origin of the notion of category, bringing in his own revolutionary import: in Aristotle categories were leges entis [laws of being], in Kant, they become leges mentis [laws of mind]. Kantian categories are no ontological contents, but synthetic forms, modes of functioning of the understanding. Since they are not related to being as such (if they were, Kant remarks against Aristotle, they would only be apprehended a posteriori and through empirical knowledge), they can be formulated on a table, a priori. Thinking is judging; therefore, there must be as many forms of pure thought [categories] as forms of judgement. Since formal logic has found 12 forms of judgement, Kant finds their correlative 12 categories. This is also a very disputed association Kant makes between his categories and Aristotle’s predicaments (likewise logic), since as manyu have shown the former had established them as categories of objects, the latter as categories of understanding, of the thinking subject. Here’s the table:

Still, it all seems very circular. Kant encourages the reader to undertake this difficult ‘leap’ into the world of the a priori for the sake of enlarging the scope of understanding beyond what can be known through experience. He just can’t live with Hume’s radical skepticism. On page 88 he seems to be saying, if you can’t cope with all this, don’t complain then that the subject is involved in obscurity, or don’t be too impatient of the obstacles on this path…etc etc. Authors always know when their text is losing the reader’s grip. But interestingly he also adds that: ‘we have a choice of only two things – either at once to give up all pretensions to knowledge beyond the limits of possible experience, or to bring this critical investigation to completion.’ (88). Well, stay with us…let’s transcend…