 NonCartesian forms of classical foundationalism have tried to combine the a priority required by non-circularity with a probabilistic form of inference, the most promising candidate being abduction, or inference to the best explanation (Russell 1912, BonJour 2003). According to this view, the best explanation of our experiences is the commonsense hypothesis that there is a mind-independent external world that conforms in some measure to these experiences and is the cause of them. The superiority of this explanation to the alternatives (idealism, a Cartesian demon, etc.) is held to be an a priori matter, thus not dependent on assuming the veridicality of the very experiences the argument is supposed to legitimate. There is a good deal of intuitive plausibility to the claim that an external world serves as the best explanation for our sense experience, but making that case in any detail, especially enough to satisfy the idealist, would require taking on some large and complex issues, like what makes one explanation better than another  (see they entry on abduction),  and—since the commonsense view is sometimes (e.g., Russell 1912, BonJour 2010) held to be simpler than competitors—what counts as simplicity, a vexed question in the philosophy of science  (see the entry on  simplicity).  William Alston (1993) offers an influential critique of abductive arguments for the reliability of sense-experience.