6.6. The Second Approximation
I think that the most promising strategy for the conceptualist in responding to worries concerning diachronic indiscriminability, especially in light of the New Experiment, is to emphasize the indeterminacy of the content of most color concepts. The relevant notion of determinacy may be spelled out in opposing terms of, on the one hand, color properties that are maximally determinate—thought of, perhaps, as points in a color solid or lines on a color spectrum—and color properties that are merely determinable—thought of, perhaps, as regions of non-zero extent in a color solid or bands of non-zero thickness on a color spectrum.
Consider the conceptual content expressible by the sentence John’s shirt was a shade of light blue. We might think of the logical form of this content as being existentially quantified: there is a shade of light blue such that John’s shirt has it. We might even allow that the content commits to there being a maximally determinate shade that the shirt has, while being noncommittal as to precisely which shade that is: there is a maximally determinate shade of light blue such that John’s shirt has it. As I shall be understanding the relevant notion of indeterminacy, the color concepts expressed in the above sentences concerning the color of John’s shirt are indeterminate. The concept deployed, LIGHT BLUE, has a content that is determinable but not determinate—there are multiple maximally determinate shades that are correctly conceived of as light blue.
An appeal to indeterminacy can help the conceptualist deal with the New Experiment in the following manner: The conceptualist may suppose that the conceptual content of the experience upon being presented with both chips at time t1 is roughly expressible as
(e1) The chip on the left has a shade of light blue that is darker than the shade of light blue on the right.
And the conceptual content of the experience at t2 is roughly expressible as
(e2) The chip on the right has a shade of light blue that is darker than the shade of light blue on the left.
The conceptualist may point out that the content of e1 and e2 differ only with respect to which chip (chip on the left v. chip on the right) is being conceived as being a shade of light blue darker than another. The concepts deployed with respect to color in e1 and e2 are the same concepts. But the failure of diachronic distinguishability may be explained in terms of the indeterminacy of the deployed color concepts. The contents of e1 and e2 are noncommittal as to which maximally determinate shade of light blue each of the presented chips have and thus the subject is at a loss to say whether the darker of the two chips at t1 is the same maximally determinate shade as the darker of the two chips at t2.
An emphasis on indeterminate conceptual contents can also account for the data of the Old Experiment. Now, like the First Approximation, the advocate of the Second Approximation’s indeterminacy-based explanation can say that the same color concept, LIGHT BLUE, is deployed at t1 and t2. But what distinguishes the First Approximation from the Second Approximation is one of emphasis: where the First Approximation emphasizes the sameness of the concept deployed, the Second Approximation emphasizes the indeterminacy of the concept deployed. We might say that the crucial difference of the two explanations is that the former attempts to account for indiscriminability in terms of the presence of the same conceptual representation on two occasions, the latter attempts to account for indiscriminablity in terms of the absence of a conceptual representation of which maximally determinate shade is present on the two occasions. (This crucial difference between the First and Second approximations will serve to further illustrate the superiority of the latter when we examine problems that arise in contemplation of phenomenal sorites in section 8.)
One line of support for the indeterminacy-based Second Approximation over the First Approximation is that the subjects in the experiments are not confident that at t1 and t2 they are presented with the same color. Instead, they lack confidence about whether the presentations at t1 and t2 have the same color. One would expect that, if the First Approximation was correct, the subjects would be judging that the colors present at the two times are the same. It seems more plausible, however, that when one is subjected to such stimuli, one will lack confidence about whether they are the same as opposed to representing them as the same.
 For other advocates of the view that experiences can have indeterminate contents see Grush (2007), Hellie (2005), and Pautz (2007).