  So far we have only an account of what it is for a sentence to be an observation sentence for a particular person. But our language is shared, as it must be if it is to enable us to communicate with one another. So we need to generalize the criterion across the linguistic community. One might at first think that the social criterion would be: if one person is disposed to assent to the sentence on any occasion on which he or she has a certain neural intake, then any other person having the same neural intake will also be disposed to assent to it. Quine gives essentially this account in (1960). As he quickly comes to see, however, it is not tenable, for it assumes that we can make sense of the idea of “same neural intake” between different people. But different people have different sensory nerves (and there is no reason to suppose that one person’s sensory nerves are homologous to those of others; see Quine 1969, chapter 6).