The primary aim of this paper is to provide the exact diagnosis of the contingent a priori debate so far by untangling complicated issues surrounding it, such as singular thought, linguistic stipulation, and epistemic justification. I will first maintain that most philosophers' arguments for or against the contingent a priori are ultimately based on one of two conflicting intuitions about linguistic stipulation: sceptics of the contingent a priori have appealed to the intuition that extra-linguistic knowledge cannot be acquired through the (...) stroke of a pen, whereas proponents of it have appealed to the other intuition that one is in a position to understand a name that one introduces by oneself into one's own language. Then I will reconstruct the sceptics' and proponents' positions in their strongest form respectively and examine where they disagree, and finally I will argue that the contingent a priori debate cannot help but end in a stalemate without further scrutiny into singular thought. From this diagnosis, I conclude that in order to appropriately judge whether a contingent proposition is knowable a priori, we must first independently investigate what the conditions for singular thought are: the contingent a priori rides on the singular thought debate. (shrink)