Why did Kant say Hume woke him up from his dogmatic slumber? How did he address the challenge Hume posed in respect of the problem of causality? In what sense does this response constitute a basis for Kant’s metaphysics?
Answer by Jürgen Lawrenz
To start with, ‘slumbers’ was a bit of an exaggeration; and today’s reader has to be made aware that the word ‘dogmatic’ did not then have the same pejorative connotations it has for us. Many if not most people were still comfortable with the idea that church dogma was simply the truth of their religious beliefs.
The difference here is the somewhat more shaky philosophical-cosmological dogma which rested on the Newtonian conception of science. Its doctrinal mainstay was that observation paired with logic would in principle suffice to achieve certainty of knowledge, given its rigorous methodology. But at the centre of this ‘dogma’ we find the theory of causality that came under fire in Hume’s skepticism. He claimed that observation of any event A triggering event B is by no means an incontestable chain of events; in fact the link between them (the ’cause’) is unobservable and in too many cases nothing other than a “constant conjunction” of those events. Hence it remains a logical possibility that this constancy will one day stop: Science cannot go beyond its inductive methodology and fasten its pronouncements on intrinsically contingent features of the world to its mast, as if they were pennants of eternal truths. Indeed, science cannot prove the necessary connection that must prevail in cause-and-effect scenarios, therefore the theory of causality is deficient in just this respect.
On the other hand, Kant saw the obvious too, that in the absence of a theory of causality, we would have to give up on our striving for certainty of knowledge. It was a difficult, thorny and contentious road, of which I can obviously give no more than a nutshell account. He began with his realisation that we humans are not passive recipients of messages from the world — we are participants in this information circuit, and this results immediately in a changed perspective on the matter. Namely., that our perceptions reveal phenomena bearing attributes that must conform to the structure of our perceptive capacities. This is a necessary precondition, for an object can only be an object for us; there are no ‘neutral’ objects, i.e. Dinge an sich, making their way into our consciousness. (I give you ultraviolet radiation as an example — we know of its existence only because we invented instruments which can penetrate more deeply into the colour spectrum than our eyes).
Now this one change, from being mere recipients to participants, changed all the rules. We are now in a position of examining our own ‘equipment’ and make deductions on all-important features of participation, namely (a) that we can know indubitably and before the event that objects must have a phenomenology that we are able to experience; (b) that all such objects and occurrences are compresent with us and situated in a location that is part of the 3D space we share; (c) that their causal interactions impinge on our understanding even in default of any theoretical scaffolding we might intellectually deduce. So these three points comprise the foundations of real knowledge on the basis of an intentional aspect of life that has a mandate to constitute it.
The upshot is, in the first instance, the rebuttal of our vain craving for empirical certainty and ‘eternal’ truths. It is not possible for finite creatures to take aim at the infinite. Hence the same criteria affect metaphysics as well — the latter understood as the theological partition of philosophy. The basic criterion is that the facts of the world are apperceived and then transformed into concepts by our faculties. Yet we can also form concepts about matters that are not derived from experience, but from teaching, stories, art and common beliefs. So there are two types of concepts, those which refer to phenomena and those which refer to other concepts. The latter, however, lacking an experiential component, must be noumena, “creatures of reason”. Which entails that they cannot be shown to exist and must accordingly be withdrawn from the list of items that are subjects of knowledge. Evidently this finding threw a spanner in the works of theology; even though Kant rebutted critics who accused him of destroying religion, whereas the opposite was the case: “I have delineated knowledge so as to make room for faith.” These words encapsulate what his readers did not wish to hear (including today): That religion is indeed one of those matters which (in Wittgenstein’s words) “we cannot speak about”, as it mere delusion to suppose that (if indeed there are gods, angels, original sin, salvation etc.), we can satisfy our longing for them by rational argumentation. These things are not transcendental, which is the basis of Kantian knowledge acquisition — they are transcendent, “beyond” our capacity for ratiocination.
I hope this will do for an initial orientation. For more information, including heaps of academic disputation, there is an abundant secondary literature, reported to amount to 17,000 items on a recent count!