 Whatever one’s view of Bayesianism, IBEs have their own shortcomings. The assessment of ‘best’ is not only a value-tinged judgment, but is notoriously tricky (especially given the ambiguous and hard to pinpoint import of the Rs in the present case). There is also the very deep question of why we should think that features which we humans find attractive in proposed explanations should be thought to be truth-tracking. What sort of justification might be available here? Furthermore, taking design to be the best explanation for something requires prior identification of the appropriate properties as design-relevant, and that recognition must have a different  basis.[8]  And again, substantive comparison can only involve known alternatives, which at any point represent a vanishingly small fraction of the possible alternatives. Choosing the best of the known may be the best we can do, but many would insist that without some further suppressed and significant assumptions, being the best (as humans see it) of the (humanly known) restricted group does not warrant ascription of truth, or anything like it.