Mark Sacks in an important article which is referred to and briefly commented on by Habermas in his introduction to TJ, makes a distinction between Transcendental constraint (TC) and Transcendental feature (TF). Let us see first how Sacks define these terms:
“TC indicates a dependence of empirical possibilities on a non-empirical structure, say, the structure of anything that can count as a mind. Such constraints will determine non-empirical limits of possible forms of experience. So here we have a direction of determination that runs from a certain transcendental structure, say of the mind, to the range of empirical forms of experience that can be actualised.”
“A merely TF on the other hand, is significantly weaker. Transcendental features indicate the limitation on what, at a time, can be envisaged as possible, and to which alternatives cannot be made intelligible as long as they retain their transcendental status. But these features are rendered transcendental only by the empirical variety of language games currently available; they are relative to the way we are currently minded, in Lear’s phrase.” (p. 178).
First let me state that Sacks uses the terms “empirical” ambiguously to describe both what is ‘experienced’ empirically and what in principle can be ‘experienced’ empirically. According to this distinction TF would be empirical only in the latter sense. This should weaken the sharp contrast Sacks makes to a certain extent though his general point remains intact. Sacks' point is that only TC can determine the form of possible experience, while TF can provide no such guarantee. However the above distinction considerably weaken Sacks' following points:
“TF, expressing limits of what we can currently envisage, might serve as constraints on what serve as constraints on what projects we undertake, what we can recognize as a viable option, etc. But the contingency of those TF means that their force as constraints in no way privileged over that of ordinary empirical constraints. This is because it is a contingent matter whether they are sustained, rather than a shift in our practices sustaining alternatives to them, whether or not we can now make those alternatives intelligible.” (p. 179).
Now the fact is that TF are in a critical sense privileged over “ordinary empirical constraints.” While we can objectify ordinary empirical constraints in toto, TF, like lifeworld or language can only be objectified partially. It is impossible for us to objectify language or lifeworld in toto.
A further point is that Sacks' sharp contrast between the necessary character of TC and merely contingent character of TF is itself a residual of the transcendental model. Once we abandon a transcendental model of the Kantian sort the sharp contrast between the necessity of intelligible and the contingency of empirical should also give way to a less sharp distinction. This is another way of saying that the distinction between intelligible and empirical is not to be conceived as a dichotomy.