This paper presents an argument for the Principle of Sufficient Reason, the PSR, the principle according to which each thing that exists has an explanation. I begin with several widespread and extremely plausible arguments that I call explicability arguments in which a certain situation is rejected precisely because it would be arbitrary. Building on these plausible cases, I construct a series of explicability arguments that culminates in an explicability argument concerning existence itself. This argument amounts to the claim that the (...) PSR is true. The plausibility of the initial cases in the series provides the basis of an argument for the PSR, an argument that can be rebutted only by drawing a line between the plausible early cases in the series and the apparently unacceptable later cases. I argue that no principled reason for drawing this line has been found and that one cannot draw an unprincipled or arbitrary line without begging the question. The paper concludes that, therefore, this defense of the PSR remains unrebutted and that we have a powerful, new reason to embrace the PSR. (shrink)