 The argument relies on a conception of scientific or physical properties that is widespread in philosophy: that physics has no place for phenomenal properties or perceptual experience. Accordingly, physics posits particles and forces, which may cause perceptual experience in a suitable perceiver, but which themselves are colorless. Jackson is certainly right that physics today does not accept something akin to phenomenal color as a fundamental physical property; rather, it accepts wavelengths and brain processes, and these possess no such fundamental property. Prior to the evolution of color-sentient beings, there presumably were no phenomenal experiences of color, hence none to be counted among physical phenomena. Nonetheless, physics, especially in the science of optics, accepts the “subjective perception of color” (Nelson 2017: 125) as an object of  study,[22]  just as acoustics accepts the experience of pitch as a physical phenomenon (Weld &amp; Palmer 1925: 322). Arguably, phenomenal experiences need not be reduced or even reducible to basic physical processes in order to be counted among physical phenomena and hence among items to be investigated in the hard sciences, including physics. Accordingly, color experience needn’t be decisively categorized as “non-physical”. Its ultimate ontology is left open. It might be a mental content as in an intentional theory or other appearance  theory.[23]  The color property might be analyzed relationally, as a surface property with the power to produce a color experience, which needn’t be a colored sense datum. The metaphysical status of phenomenal experience need not be decided in order for the conditions of such experience to be examined in the science of physics.