  Despite the failure of these attempts to provide a rigorous empiricist criterion of meaning, Ayer continued to hold that there was a close connection between evidence and meaning, maintaining that a satisfactory account of confirmation was needed before a fool-proof criterion of empirical meaning could be supplied. Given later doubts about whether any theory of confirmation could provide a foundation for a theory of meaning (Quinean doubts relating to the impossibility of ruling out any facts as possibly bearing on the truth of any sentence), it remains unclear as to how the evidence-meaning connection can be circumscribed. (For a review of other attacks on, and adjustments to, the verification principle, see Wright 1986, 1989.)