According to Davidson, whatever is non-conceptual cannot play the role of evidence, to the effect that nonconceptual sensory experience is epistemically insignificant. Thus he defends coherentism, according to which beliefs are justified, not by virtue of relations between beliefs and the world, but only by virtue of relations between beliefs. But McDowell objects to this view. According to him, empirical thinking must answer to how things are, so that it needs to be rationally constrained by experience; but coherentism isolates one's belief system from the world, by failing to satisfy the 'external rational constraint' of empirical thinking. In addition, McDowell construes this constraint as an object-language relation between what is conceptual and what is real, and claims that the world itself has to be conceptual in order for this constraint to be satisfied. In this paper, I argue that McDowell's isolation objection is unsuccessful. For this thesis, I argue, first of all, that the external rational constraint must be understood on a meta-linguistic level, and that this constraint understood thus does not conflict with coherentism. In addition, I argue that the view that coherentism isolates one's belief system from the world is based on a false assumption that empirical content can be given independently of the world. Coherentism does not deny that the world is already given in our use of empirical concepts through linguistic learning and linguistic practice. Moreover, I argue that we can satisfy the external rational constraint without embracing excessive Hegelianism, which takes the world itself to be conceptual, when we understand the external rational constraint on a meta-linguistic level.