 The above example is used by Weisberg (2009b) not just to argue against the Principle of Jeffrey Conditionalization, but also to illustrate a more general point: that principle is in tension with an influential thesis called confirmational holism, most famously defended by Duhem (1906) and Quine (1951). Confirmational holism says roughly that how one should revise one’s beliefs depends on a good deal of one’s background opinions—such as the opinions about the quality of the lighting, the reliability of one’s vision, the details of one’s experimental setup (which are conjoined with a tested scientific theory to predict experimental outcomes). In reply, Konek (forthcoming) develops and defends an even more flexible version of conditionalization, flexible enough to be compatible with confirmational holism. For more on confirmational holism, see the entry on  underdetermination of scientific theory  and the survey by Ivanova (2021).