On Transcendental Arguments

Following Kant, Stroud conceives of transcendental arguments as attempting to refute the sceptic about “the existence of things outside us.”(Stroud [1968], p. 242.) Stroud sees TAs as directed at global scepticism. The global sceptic simultaneously calls into question all our beliefs about the external world by pointing out that all the evidence we have available is compatible with the world being radically different from the way we take it to be. The global sceptic does not only question some particular empirical claim (i.e., that cup is larger than my hand) which we can verify as true or false by a simple observation. Rather, the global sceptic insists that the very methods (i.e., the empirical criteria) we use to verify our empirical claims are no good since they are compatible with there being no cup at all. The global sceptic’s argument may be summarised as follows:

(GS1): Any justification for one’s EW beliefs must be derived from the fulfilment of some empirical criteria.

(GS2): The very best empirical criteria one has available are compatible with the falsity of one’s EW beliefs.

(GS3): If one’s empirical criteria are compatible with the falsity of one’s external world beliefs, then empirical criteria is not adequate to justify one’s EW beliefs.

(GS4): Therefore, one’s EW beliefs are not justified

Carnap points out that traditionally, anti-sceptical arguments have tried to avoid (GS4) by rejecting (GS2). That is to say, they involve raising the standard of the empirical criteria under consideration (e.g., by demanding certainty etc.) so as to rule out the possibility of the standard being met simultaneous with the falsity of one’s EW beliefs. However, he notes that attempting to refute the global sceptic by this means is moribund since it involves trying to establish that one’s empirical criteria is adequate by appeal to evidence that has its status as evidence based on the very empirical criteria that is being called into question. This anti-sceptical strategy involves responding to a challenge from the “outside” from “within”, like arguing that the Bible is the word of God by citing biblical passages. While effective when directed at one who already believes, it is ineffective with the sceptic.

What is supposed to be distinctive about TAs is that they attempt to avoid (GS4), not by rejecting (GS2) but by rejecting (GS1). In this regard, TAs represent a departure from the type of approach Carnap impugns. For Kant, rejecting (GS1) involved the employment of synthetic apriori truths as an alternative to collecting direct empirical evidence. Put negatively, TAs are committed to denying that the only source of justification for our EW beliefs is experience. Put positively, TAs claim that the possibility of experience itself presuppose certain thoughts or concepts which could only be had if there is an external world. It is believed that by appealing to the necessary conditions of experience, rather than to experience itself, we may gain justification for some of our beliefs about the world.

TAs typically take some fact, M, about our mental life (typically one that the sceptic herself would accept), adds that some extra-mental fact, P, as a necessary precondition for the possibility of M, and concludes (on that basis) that the extra-mental fact holds. Thus, we arrive at the following general structure for an anti-sceptical TA:

(T1): M is possible
(T2): P is a necessary precondition for the possibility of M
(T3): Therefore, P

The locus classicus of the TA strategy is Kant’s argument in “The Refutation of Idealism” where he seeks to establish that “the mere, but empirically determined, consciousness of my own existence proves the existence of objects in space outside me.” (B275) Kant argues that one’s consciousness of oneself as determined in time depends on the application of the concept of alteration to one’s own mental states. But one could only acquire the concept of alteration from having objective alteration exhibited in one’s sensory experiences. Moreover, the objective alteration exhibited in one’s experience cannot be based on regularities in the experience itself since being able to recognise any such regularity requires organising one’s experience in time. Thus, the possibility of organising one’s experiences in time requires relating changes in those experiences to objective alteration. Since we do make judgements about the temporal order of own mental states, then we must have experience objective alteration.

We may reformulate Kant’s argument to fit the (T1)-(T3) format outlined above as follows:

(K1): Judgements about the temporal order of one’s own mental states are possible
(K2): Judgements about the temporal order of one’s own mental states are possible only if one has experienced independent, enduring substances undergoing alteration.
(K3): Therefore, independent enduring substances exist

Thus, Kant seeks to establish the truth of a fact about the EW, by an argument that relies on the necessary conditions for the possibility of experience, rather than a direct appeal to experience itself. Moreover, Kant attempts to establish his conclusion by appeal to a starting premise (concerning our mental life) that the sceptic (i.e., the idealist) herself presupposes in formulating her objection. Thus, Kant insists that “the game that idealism plays has with greater justice been turned against it.”[B276]


Reference:

Stroud, B. [1968], “Transcendental Arguments”, The Journal of Philosophy 65, 9: 241-256.