1. Ernst Mach Spies a Shabby Pedagogue. In The Analysis of Sensations (Dover, 1959, p. 4, n. 1) Ernst Mach (1838-1916) offers the following anecdote:
Not long ago, after a trying railway journey by night, when I was
very tired, I got into an omnibus, just as another man appeared at
the other end. 'What a shabby pedagogue that is, that has just
entered,' thought I. It was myself; opposite me hung a large
mirror. The physiognomy of my class, accordingly, was better know
to me than my own.
When Mach got on the bus he saw himself, but not as himself. His first thought was one expressible by 'The man who just boarded is a shabby pedagogue.' 'The man who just boarded' referred to Mach. Only later did Mach realize that he was referring to himself, a thought that he might have expressed by saying, 'I am a shabby pedagogue.'
Clearly, the thought expressed by 'The man who just boarded is shabby' is distinct from the thought expressed by 'I am shabby.' After all, Mach had the first thought but not the second. So they can't be the same thought. And this despite the fact that the very same property is ascribed to the very same person by both sentences. The difference emerges quite clearly if we alter the example slightly. Suppose Mach sees that the man who has just got on the bus has his fly open. He thinks to himself: The man who has just boarded has his fly open, a thought that leads to no action on Mach's part. But from the thought, I have my fly open, behavioral consequences ensue: Mach buttons his fly. Since the two thoughts have different behavioral consequences, they cannot be the same thought, despite the fact that they attribute the very same property to the very same person.
But if they attribute the same property to the same person, what exactly is the difference between the two thoughts?
Linguistically, the difference is that between a definite description ('the man who just boarded') and the first person singular pronoun 'I.' Since the referent (Frege's Bedeutung) is the same in both cases, namely Mach, one will be tempted to say that the difference is a difference in sense (Frege's Sinn) or mode of presentation (Frege's Darstellungsweise). Mach refers to himself in two different ways, a 3rd-person objective way via a definite description, and a 1st-person subjective way via the first-person singular pronoun.
If this is right, then although there are two different thoughts or propositions, one indexical and the other non-indexical, it might seem that there need only be one fact in the world to serve as truth-maker for both, the fact of Mach's being shabby. This is a non-indexical fact. It might seem that reality is exhausted by non-indexical facts, and that there are no such indexical or perspectival facts as those expressed by 'I am shabby' or 'I am BV' or 'I am the man who just got on the bus.' Accordingly, indexicality is merely a subjective addition, a projection: it belongs to the world as it appears to us, not to the world as it is in reality. On this approach, when BV says or thinks 'I,' he refers to BV in the first-person way with the result that BV appears to BV under the guise of 'I'; but in reality there is no fact corresponding to 'I am BV.'
2. But is this right? There are billions of people in the world and one of them is me. Which one? BV. But if the view sketched above is correct, then it is not an objective fact that one of these people is me. That BV exists is an objective fact, but not that BV is me. BV has two ways of referring to himself but there is only one underlyingobjective fact. Geoffrey Maddell strenuously disagrees:
If I am to see the world in a certain way, then the fact that the
world seen in this way is apprehended as such by me cannot be part
of the content of that apprehension. If I impose a subjective grid
on the world, then it is objectively the case that I do so. To put
it bluntly, it is an objective fact about the world that one of the
billions of people in it is me. Mind and Materialism, 1988, p.
Maddell's point is that the first-person point of view is irreducibly real: it itself cannot be a subjective addition supplied from the first-person point of view. It makes sense to say that secondary qualities are projections, but it makes no sense to say that the first-person point of view is a projection. That which first makes possible subjective additions cannot itself be a subjective addition.
Consider the phenomenal redness of a stop sign. It makes sense to say that this secondary quality does not belong to the sign itself in reality, but is instead a property the sign has only in relation to a perceiver. In this sense, secondary qualities are subjective. But to say that subjectivity itself, first-person perspectivity itself, is a subjective projection is unintelligible. It cannot belong to mere appearance, but must exist in reality. As Madell puts it, "Indexical thought cannot be analysed as a certain 'mode of presentation', for the fact that reality is presented to me in some particular way cannot be part of the way in which it is presented." (p. 120)
3. Trouble for materialism. According to materialism, reality is exhausted by non-indexical physical facts. But we have just seen that indexical thoughts are underpinned by indexical facts such as the fact of BV's being me. These facts are irreducibly real, but not physically real. Therefore, materialism is false: reality is not exhausted by non-indexical physical facts.