Indiscriminable but not Identical Looks : Non-vague Phenomenal Predicates and Phenomenal Properties

A deep-rooted assumption concerning indiscriminability between visual appearances is the following: two things are indiscriminable in look to an observer at a particular instant of time if and only if they look the same to that observer at that particular instant of time. I argue that this deep-rooted assumption may be false. The argument is in two steps. First, it is argued that indiscriminability between appearances may be non-transitive. Then it is argued that non-transitive indiscriminability between appearances is inconsistent with the deep-rooted assumption. It is therefore deduced that the deep-rooted assumption may be false. Finally, I argue that if the deep-rooted assumption may be false, then one of the premises of the phenomenal sorites paradox may be false too. And this leaves open the possibility that vague phenomenal predicates are coherent and that phenomenal properties are ontologically legitimate.