 At least two main problems arise, however. The first one is more technical in nature. Modelling rational uncertainty concerning logical facts (such as \(h \wedge k \vDash e\)) by probabilistic means is no trivial task. Garber (1983) put forward an influential proposal, but doubts have been raised that it might not be well-behaved (e.g., van Fraassen 1988; a careful survey with further references can be found in Eva and Hartmann forthcoming). Second, and more substantially, this solution of the old evidence problem can be charged of being an elusive change of the subject: for it was Mercury’s data, not anything else, that had to be recovered as having confirmed (and still confirming, some would add) Einstein’s theory. That’s the kind of judgment that confirmation theory must capture, and which remains unattainable for the predictivist Bayesian. (Earman 1992, 131 voiced this complaint forcefully. Hints for a possible rejoinder appear in Eells’s 1990 thorough discussion; see also Skyrms 1983.)