Kant’s critical philosophy is an attempt to ground the metaphysical, which Kant claimed was replete with ‘obscurity and contradiction’ (A viii). Kant attempted to show that there can be a meaning to life established through human reason that does not require the intuitive abilities to sense the world as it exists in itself. Rather, we should embrace our limitations; accept the ‘unhinging’ of orthodoxy (Deleuze; vii). ‘We…have to figure things out for ourselves’ (Pinkard, 20), truth is ‘self-generated’ (45), imbuing man with the freedom to shape the world in accordance with reason, as opposed to having life determined by contingent normativity.
Rationalism’s claim that man saw the world ‘uncontaminated’ (Scruton; 2001, 24), with man’s cognitive abilities working in ‘pre-established harmony’ with no epistemic limitations, Kant claimed, was ‘obscure, confused and useless’ as reason requires an ‘antecedent critique of its own capacity’ (B xxxvi), necessitating a grapple with the epistemological: how do we know what we know? This question led Kant to see the virtues of Humean empiricism: what we know is generated by experience, yet, departing from Hume, seeing that experience is ordered by necessary features of man’s cognition (102), thus moving from ‘psychological subjectivity’ to ‘transcendental subjectivity’ (Deleuze; 11).
For Kant, empiricism was not an adequate base for knowledge, as one must ‘go beyond’ (Deleuze; 10) experience to have knowledge; empiricism yields no necessity (A 2) only contingency (B 4). For Kant, there are principles that necessarily govern experience and perception that are conditions for experience itself. Space, time, and causality, for Kant, are self-generated transcendental ‘pure’ constructs of the mind that allow us to have a relationship with the real whilst accepting this relationship is limited; we can never know the thing in itself. Empirical reality is man’s confined apprehension, the actuality of the world is transcendentally ideal; our embodiment prohibits us from directly experiencing it.
Our perception, what Kant referred to as the understanding, blocks us from apprehending noumena (the unperceived object). Human cognitive faculties severed the tie to the ‘real’, leaving the subject epistemically constrained. All we can know is how we perceive the world upon our causal interaction with it and our apprehension of externality requires categorization and rationalisation. The world revolves around our perceptions, and our perceptions allow us to apprehend knowledge of the world through ‘universal self-consciousness’ (Pinkard; 41). If, upon empirical investigation we establish necessity, we have established a ‘synthetic a priori’ truth, providing the basis for knowledge which was undermined by Hume’s empiricism. Kant believed that these findings addressed or elucidated every metaphysical problematic previously grappled with.
Like the social revolutions of the time, Kant’s ‘Copernican Revolution’ inverted the pre-existing power structures. Kant’s philosophy purportedly provided man with the abilities needed to establish freedom and truth, without a necessary connection with God, ‘think for ourselves’. This created a new teleology: man’s role, post-Kant, is to establish necessity and universality, shaping the world in accordance with reason and creating the kingdom of ends, all we need is the courage to do so.
 Metaphysics here should be read with the widest scope possible