Larmore (2002, ‘Attending to Reasons’, in N. Smith (ed.) Reading McDowell: On Mind and World, London: Routledge, pp. 193-208) writes:
.. the Given cannot serve as a justification for a belief, if it lacks conceptual articulation; yet to the extent that it is shaped by an understanding of the world we already possess, it cannot count as simply "given". (p. 196)
Larmore may be right that something like this is supposed to be 'the well-known trouble with [the] "foundationalist" approach'. But I don't see the force of the dilemma. We can accept the truth of the first horn, the claim that conceptual articulation is required in order for sensory input to justify a belief. But we do not thereby impale ourselves upon second horn. For provided this conceptualized sensory input is ‘shaped’ by an ‘understanding of the world’ which is itself shaped in response to what is given to us in (unconceptualized) sensory input, there is no reason to think that this understanding in any way distorts our experience of the world. Rather, we can hope that the conceptual shape of our conceptualized sensory input reflects the structure of the world.