Why does the chaotic ‘matter’ of sensations submit itself so tamely to the forming of the mind?  How can the a priori necessities of thought, which are the ‘presuppositions’ of the complexities Kant loved, operate upon so alien a stuff as the sensations are assumed to be?  And, after all, was not Kant a bit premature in proclaiming the finality of his analysis and of his refutation of empiricism for all time?  The searching question, Why should the future resemble the past? had received no answer, and so might not the mind itself, with all its categories, be susceptible to change?  Was it certain that the miracle whereby the data presented to our faculties conformed to them would be a standing one?  Had not Kant himself as good as admitted that our faculties might distort reality instead of making it intelligible?

The truth is that at this point Kant is open to a charge against which the assumptions he shared with Hume admit of no defence.  Hume had been the first to discover that we are in the habit of trying to rationalize our sense-data by putting ideal constructions upon them, though he had abstained from sanctifying the practice by a hideous jargon of technical terminology.  But this way of eking out the facts only seemed to him to falsify them.  Truth in his view was to be reached by accepting with docility the sensations given from without.  To set to work to ‘imagine’ connections between them, and to claim for them a higher truth, had seemed to him an outrage.  What right, then, had Kant to legitimate the mind’s impudence in tampering with sensations?  Was not every a priori form an ‘imagination,’ and a vain one at that?

To these objections the Kantian school have never found an answer.  They have simply repeated Kant’s phrases about the necessary ‘presuppositions’ which were to be added to Hume’s data.  The English psychologists (the Mills, Bain, etc.) exhibited a similar fidelity.  They never accepted the a priori, but relied on ‘the association of ideas’ to build up a mind out of isolated sensations.  But was this expedient really thinkable?  For if all ‘sensations’ or qualities are separate entities, how can the addition of more ‘distinct existences’ of the same sort really bind them together?  If in ‘the cat is upon the wall,’ ‘upon’ is a distinct entity which has to relate ‘cat’ and ‘wall,’ what is to connect ‘cat’ with ‘upon’ and ‘upon’ with ‘wall’?  The atomizing method carried to its logical extreme demands that not only ‘sensations’ but also ‘thoughts’ should be essentially disconnected, and then, of course, no thinking can cohere.