Subreption

During early modern period in Europe, the meaning of "subreption" changed. "[W]riters began to speak of the error of subreption in a more general sense, as opposed to the [Ancient Roman] legal concept of a crime of subreption. Among the German rationalist philosophers who continued to circulate, refine, and redefine the term in the eighteenth century, Christian Wolff stands out as particularly significant for Kant's interest in subreption. Wolff defines the vitium subreptionis as a confusion of "knowing" (erkennen) with "experiencing" (erfahren), which we commit whenever we think ourselves to be experiencing something that is merely a product of the intellect. This was the main meaning attached to the term as it was adopted into general scholarly usage in Germany by the middle of the eighteenth century."[3]

Kant adopted the term subreption in his early work. For Kant in his Inaugural dissertation "[w]hen we attach a predicate involving sensible conditions to a concept of the understanding, we must bear in mind that it merely denotes conditions 'in the absence of which a given concept would not be sensitively cognizable'. If we deceive ourselves into thinking that the predication has some objective force (that is, that it has anything to say about the conditions of possibility of the object itself), we cross over into subreption. For Kant, the error of subreption is thus the conflation of a 'sensitive condition, under which alone the intuition of an object is possible' and 'a condition of the possibility itself of the object'". In the same dissertation, an example of subreption for Kant is the axiom "every actual multiplicity can be given numerically, and thus every magnitude is finite"; Kant considers this axiom to be subreptive because the concept of time is introduced surreptitiously as, Kant says, the "means for giving form to the concept of the predicate". This axiom implies that the infinity is impossible in itself, however Kant argues that infinity is not impossible in itself, but that infinity is only impossible to imagine for the human mind because said mind relies on sensitive conditions.[4]