Watching Avatar over last Christmas, already years after the hype, I was thinking of the scene where the earthling is taught to ride the flying horse by concentrating his thoughts on where he wants to go. It is common in plots where nature is somehow directly accessed and more integrated to human ways to feature some measure of mind reading. I then started wondering how do I go about mind reading. I wanted to be very open to possible episodes of matter reading – salt detecting water, ticks registering mammals, bees seeking flowers, a ball reading off the presence of a wall and animals noticing body temperature variation. What is the content of what is read is a common issue in both mind and matter reading. Does the tick read off a species or an increase in comfort? Or could we circumvent the content issue altogether by saying that they merely react? The frog reacts to the passing fly – but what does it react to when it reacts to the passing fly?
The problem with mind reading – like the flying horse supposedly could do – is that of private content. The human character's mind – or for that matter, his brain connections as they say in the film – is arranged in a way that cannot be read without a compiler. It is like my own private mess where I can find last month bill in a page of a book on Anaxagoras but no one else could find it. The problem of private content is what I take Wittgenstein was hinting at around sections 250 to
350 of the Investigations. Consider the example in section 257 – one of my favorites. The ingenious child concocted a private word for toothache after experiencing an episode of toothache without expressing any public signs of pain (yelling, complaining etc). The issue is whether she can go on applying the private word to correct cases of toothaches (and not to itches in the mouth, to pains in the finger, to metallic sounds or to whatever she finds relevantly similar to the inaugural episode of her private word). If she yells, for instance, an adult can teach the public word to her because there is a common, publicly observed action associated with the ache. Further, if someone yells and presses her hand against her mouth, other people can go and do expression-reading to detect the pain.
What is at stake in mind-reading is how much of it boils down to matter-reading. The flying horse can maybe read not the connections in the rider's brain but rather how this connection affects his body. The horse can exploit the regularity between wanting to go ahead and some features in the body. Thinking is not just a matter of neural connections but also about impact on cells, hormones, neurotransmitters etc. Memory is in the body – and so is mind-reading; what is called intuition involves a measure of exploiting traces left in the matter. Surely, conceptual abilities could make it very difficult the task of matter-reading thoughts. In Wittgenstein's discussion of William James' Mr Ballard (section 342 of the Investigations), he wonders how can the deaf-mute man know that in those rides long before acquiring the rudiments of written language he was wondering about God and the world. One possible answer, albeit possibly not terribly plausible, would be that he detected the same body impressions he had earlier later in his life when he could think in public words. Detection is a matter of finding resemblances – it is about the spontaneity. Sometimes these resemblances are reflected on the body so that they can be detected independently. Mr Ballard has some changes in his body related to a content – say, thinking about God. Two resemblance detectors coincide – the one that depends on the concept “God” and the one dependent on the body change. That they coincide (enough) is a fortunate chance. But isn't matter part of the story to be told about mind-reading?