§1 It is not always truc that rccoghizably valid reasoning from known, or othcrwisc cpistcmically warrantcd prcniiscs, can bc cnlistcd to produce knowledge, or other epistemic warrant, for a conclusion. The counterexamples are cases that exhibit what I have elsewhere called warrant transmission-failure. It is nowadays widely accepted that there are indeed such counterexamples, though individual cases remain controversial. One such controversial case is the so-called McKinsey paradox. The paradox presents as a simple collision between three claims that many would find attractive: