Metameric Whiteness and Absence of Causal Factors

Olaf Müller presents a supposedly empirically equivalent theory to Newtonian optics, which in his view is therefore threatened by underdetermination. This threat could even be expanded to modern physics, since this branch of physics is partly based on Newton’s theory. In this paper, I will show that Müller’s alternative theory contains an ill-defined concept, viz. the definition of whiteness as the absence of optical causal factors. This results from a fundamental property of whiteness: for every source of white light there exist metameric sources. I further argue that this cannot be reconciled by borrowing other concepts from modern physics, as is, I will show, tacitly presupposed in Müller’s argument. As a consequence, his alternative theory is not empirically equivalent to Newtonian optics and his argument in favour of underdetermination fails.