Is the color green a property of the grass, the photon, or the detector?
Bertrand Russels mind bending argument in full:
i) If naive realism is true, then things are what they seem, and we can study how things seem in order to determine what things are. This process, Russell believes, is synonymous with physics. For instance, a blade of grass seems to be green, therefore a blade of grass is green.
ii) But by studying how things seem, we are lead to conclude that things are decoupled in some way from what they seem. In other words, by studying a blade of grass one is led to conclude that there are two objects, the grass, and the effect the grass has on the retina via the photon.
“We think that grass is green, that stones are hard, that snow is cold. But physics assures us that greenness of grass, hardness of stone, and coldness of snow are not the greenness, hardness, and coldness that we know in our own experience, but something very different. The observer, when he seems to himself to be observing a stone, is really, if physics is to be believed, observing the affects of the stone upon himself”
iii) Finally, because the observed and the observation are separate entities, Russell concludes that in fact things are not what they seem, and naive realism is false.
“Thus, science seems to be at war with itself: when it means most to be objective, it finds itself plunged into subjectivity against its will. Naive realism leads to physics, and physics, if true, shows that naive realism is false. Therefore, naive realism, if true, is false, therefore it is false.”