I want to look at the broadly Davidsonian idea of “dual descriptions” of mental and physical phenomena, especially the idea that “reason” and “cause” represent different functions of a token-identical item. To do this, I’ll use a musical analogy.
In Western music theory, chords are often identified and described in terms of what they do in a musical context. The same chord may be give two different descriptions, depending on function. A typical example is the four-note chord consisting of the intervals of a major 3rd, minor 3rd, and another minor 3rd(or augmented 2nd; I’ll explain the (non)difference in a minute), stacked one atop the other with the top note of the first interval forming the bottom note of the next.
This four-note chord can be described as either a dominant 7th chord or an augmented 6th chord (the so-called “German 6th”), depending upon the musical context. The details don’t much matter, except to say that notes, and intervals, can be “spelled” different ways using our Western alphabetic system of designating notes. A particular spelling will usually be chosen to help the musician understand the functional role of the musical item. So in this case, if the chord is being described as a dominant 7th, the top interval will be spelled as a minor 3rd; if it’s an augmented 6th, that same interval will be spelled as an augmented 2nd. This is the same principle – known as “enharmonic spelling” – that is demonstrated in the more familiar example that the notes C# and Db are identical, just spelled differently.
The important thing is that both these descriptions of the four-note chord are at the same level – they are both functional descriptions, intended to shed light on what the chord does in a particular context. (Again, not to get too far into the weeds, but the chord can resolve in two different “correct” ways, according to 19th century theory, and the description of the chord will show which way it’s going to resolve.) Both descriptions assume the same subject matter, so to speak: four notes arranged in a particular structural relation, as described. (For that too is a description; but not a functional one.)
Bear with me; the end of the music lesson is in sight!
So, is there a different level of description, when it comes to a musical chord? Sure: the acoustic properties of the notes themselves. These are expressed in frequencies, usually in terms of cycles per second of vibration (Hertz). So another way to describe the note “middle C”, for instance, would be to call it “the note that vibrates at 261.63 Hz”. And we can expand this description to include the other three notes comprising our chord, all of which have precise Hz descriptions. Combining all four notes, finally, we could describe the total chord as a simultaneous sounding of the four frequencies, described in Hz. (There’s another whole story about what has to happen for a frequency to be considered a pitch in music, such as middle C, but that’s a side issue.)
An interesting point to keep in mind is that, in order to use this description, we have to pick a particular note for the chord to be built on, whereas the functional description is abstract; it applies to any chord that’s organized in the required way. Musicians pinpoint particular instances of abstract chordal shapes by using the alphabetical name of one of the notes, usually the bottom note.
Now we can start to see a glimmer of an analogy with the physical/mental problem. There’s good reason to say that the Hz description of notes is the foundational or basic description – the “scientific” description, if you like. It is the underlying “something” upon which our functional descriptions are premised. We can even invoke a sort of causal arrow: An underlying acoustical reality is required for there to be any functions, but we do not need the functions in order for there to be acoustics.
Similarly, many people want to say that brain states or neuronal firings are the physical reality upon which thoughts must supervene. We’re not quite at the point where we can give a “brain description” of any given thought, in the same way we can give the frequency of a note, but we’re getting close, and there seems no reason in principle why it wouldn’t be possible. So, if we grant this, then in theory we could re-describe any thought in the “brain description” language.
What would this be like?
We can return to the musical analogy for some insight. Why don’t musicians talk to each other using frequency descriptions, despite the fact that these descriptions are readily available and based on a fairly simple system of nomenclature? Well, we do, sometimes; in recording, we often need to discuss musical tones in terms of Hz, because we need to know the acoustic properties in order to get a piece of recorded music to sound better. (Musicians will know that I’ve vastly oversimplified how frequencies appear in music; all natural tones have overtones, also expressed in Hz, which dramatically affect how a note sounds and combines, though not its basic pitch.)
But when performers talk to each other, they use the “higher” level of description. They call a C a C, and not 261.63 Hz. Why? Several reasons. First of all, “261.63 Hz” is too precise; it refers only to middle C, as I’ve explained, and often musicians think in terms of abstract pitch in general, not a specific octave. But more basically, it’s just too cumbersome. We came up with “middle C” and the rest of the alphabetic system to (more or less) describe certain frequencies, and it prospered because it’s so easy to use.
But there’s another reason as well: We didn’t have access to the Hz vocabulary when we first began talking about, and playing, music. We didn’t know we were describing frequencies. Going back to Pythagoras, at least, musicians knew that notes stood in semi-mathematical relationship to each other, and that these relationships did not depend on which notes were involved – the relationships were abstract. What they didn’t have was an acoustic language in which to describe this. In other words, they knew that the ratio of root to octave was 2:1, based on listening to different lengths of strings vibrate, but they didn’t know of what it was a ratio. So by the time the science of acoustics came along, the musical vocabulary at the functional-harmonic level was very firmly established, and switching would have been difficult even if it weren’t so cumbersome.
Again, notice the similarities with the physical/mental conundrum. Humans have, for thousands of years, described thoughts in terms of their “subject” or “content” or “intension” or “meaning,” and developed elaborate ways to describe how thoughts do or don’t go together to get certain jobs done. What I called “brain descriptions” didn’t exist. Instead we had “logic,” or “rhetoric,” or “poetry,” or “politeness.”
So far, so good, as an analogy. But here’s where I think it breaks down, and the physical/mental problem assumes a unique configuration.
We could imagine a Davidsonian “anomalous monism of music,” in which the chord “C dominant 7th”, played at a certain time and place, is token-identical to its acoustical substrates. But that chord would not be type-identical to the four Hz descriptions beginning (if the chord starts on middle C) with “261.63 Hz”. Rather, we would have two different descriptions of the same thing, just as we allow reasons and causes to serve as different descriptions of . . . but here’s the problem.
Different descriptions of what? What does that innocent phrase “the same thing” refer to here?
We know how to answer that question when it comes to music: “C dominant 7th ” and “261.63 Hz . . . et al.” both describe, or identify, an acoustical event – the first in terms of function, the second in terms of acoustical composition. But what is the analogous way to answer the question about thoughts and neurons? Should we just say that neuronal firing is what happens, and that thoughts are a “functional description” like “dominant 7th”? But what is the function that requires the re-description? What are thoughts doing that neuron-firings are not doing?
The thought “My cup is yellow,” when thought by me at a specified time and place, is token-identical to whatever pattern of neuron-firing takes place simultaneously, if we adopt the Davidsonian scheme. But what we usually call the propositional content (or however we want to name the feature which could allow that thought to function as a reason rather than a cause) is not type-identical.* If “My cup is yellow” were a premise in an argument, it would not be possible to substitute the “brain description” language, in terms of neurons firing at a particular time and place, and still have the argument go through. If we could make such a substitution for all the statements in the argument, we would still not have a valid conclusion. At best, we might have a blueprint showing why a certain brain event causes another brain event (whether in a lawlike fashion or not; I’m not aware that Davidson talked much about brain events causing other brain events), but this isn’t equivalent to providing reasons why a certain proposition entails another.
[* Another possibility: Are “My cup is yellow” (thought by me, now) and the accompanying neural firings extensionally equivalent? I would welcome others’ opinions, but I don’t think they are. I find it hard to accept that “My cup is yellow” has an extension, so I don’t think the concept of extensional equivalence is going to help us here.]
This is all either very apparent or quite mysterious, depending on your philosophical commitments. I believe it’s apparent, if we allow that something like Sellars’ Space of Reasons exists at all. (And that, I freely admit, isn’t obvious, but I operate on the premise that it’s likely true.) Asking a pattern of neuronal firing to explain an argument is a category mistake, on this view. The type-non-identity is crucial.
So why doesn’t this continue to conform to the musical analogy? This is where – no doubt to the despair and impatience of many – we have to invoke the Hard Problem. We understand how the translation from an acoustic description of our four-note chord to its functional re-descriptions works. We know what the functions are that we want explained, and we understand why a description like “C dominant 7th chord” can supervene on the acoustic phenomenon which is also describable, in a much more cumbersome fashion, in terms of four Hz numbers. All this is possible because we agree that the acoustic-level description is the more basic. The functional description “C dominant 7th” just is a way of showing what the acoustical-level phenomenon can be used for.
Could we ever say that about neuron-firings and thoughts? Does Davidson’s monism ask us to make a similar agreement about the physical basis of thoughts? Ontologically (not necessarily descriptively), we’re asked to agree that the physical is indeed basic – physical stuff is all there is, if we’re inventorying the items that may be found in the world. But Davidson, as I read him, doesn’t insist that the physical description must be basic. In fact, he denies it. It would back him into the position of saying something like “Well, if you want the most basic description of my thought ‛The cup is yellow,’ you’ll need to discover the corresponding pattern of neuron firing.” He’s not saying that – though that is exactly what we would say, using the appropriate vocabulary, about a musical event like a chord.
The problem, then, is: Is there a “description-neutral” way of describing what the “thing” is in the phrase “the same thing”? I don’t see how there can be, when “the same thing” is meant to refer to whatever is being described in both physical and mental language. We could use either description – physical or mental – to name the event in question, but since neither description is basic, we don’t know what it would mean to compare them along the axis of “sameness”.
How do we get from “p describes X” and “q describes Y” to “X and Y are the same thing”? The missing premise, presumably, is “p and q describe the same thing”. But how would we know this, without a previous description of X/Y which is neither the physical nor the mental description? This is either viciously circular, or else just incoherent.
In short, it seems that we need a stipulated “basic description” before the concept of “same description” can really get off the ground. This usually isn’t problematic – most items have a basic description – but I’m arguing that it becomes so in the mental/physical conundrum.
To conclude: We would need to be more physicalist than Davidson if we wanted to claim that the ontological primacy of the physical results in a “basic description” that is also primary. Davidson doesn’t say that, and nor should we. Neither “cause” (physical) nor “reason” (mental) is a basic description in the way that the Hz language is a basic description of musical tones. So we’re left with a puzzle about how to talk about the relation between these two types of description. Which in the end is another way of saying that the Hard Problem is still opaque to us.