Well, you’ll note that I always specified a macroscopic object. Putnam solves the problem differently, by requiring an open system: if even those two particles are in continuous interaction with an environment, they will effectively traverse an arbitrary number of distinguishable states. That’s all that’s needed.
Fundamentally, the argument is nothing but this: take a FSA with n states, s[sub]1[/sub], s[sub]2[/sub],…,s[sub]n[/sub]. Any computation carried out using this FSA is a sequence of those n states. Say, without loss of generality, that sequence is s[sub]1[/sub]s[sub]3[/sub]s[sub]8[/sub]. Knowing this sequence is tantamount to knowing the result of the comptuation: there is a table such that it takes the states to human-intelligible results.
You can imagine each state to be, for example, the entire configuration of a PC—all the bits in its memory. Initialized in a starting state, it will then transition to various other states—changing the contents of its memory. This is the performance of the computation. At some point, it must either repeat (since we have a finite memory), or reach some final state. If it reaches a final state, then the configuration it has at that point, the data in its memory, is the result of the computation. Using a suitable table, you can translate the memory content to something human-intelligible—say, the first k digits of pi. This is the result of the computation.
All you need, in order to perform that same computation using a rock, say, is for that rock to have a sufficient amount of states—which as I said, can always be achieved by a sufficient fine-graining of its phase space (for a macroscopic object; for an open system, you have likewise a guarantee of sufficient states, by noting that it will, in general, never revisit the exact same point in phase space twice). Then, you only need a mapping of the rock’s states to the states of the FSA. Using this mapping, you can observe the rock, and deduce the evolution of the FSA—in our example, the sequence of states s[sub]1[/sub]s[sub]3[/sub]s[sub]8[/sub]. Where you get that mapping from is of no consequence—the argument needs only for it to exst.
So having the rock in hand, and the mapping, you can deduce the exact sequence of states the FSA goes through. Know knowing how to translate that sequence to something human-intelligible, you can, from there, obtain the result of the computation. But this translation is once again just a mapping—say, from states of the FSA to numbers. You can compose this mapping with the mapping from states of the rock to states of the FSA, to give you a mapping from states of the rock to something human-intelligible.
But then you’re in exactly the same situation you were with the original FSA in hand: the FSA performs some evolution, which, using your mapping, you can translate into, say, the digits of pi. In exactly the same way, the rock performs some evolution, which, using your mapping, you can translate into the digits of pi. So with the same justification you had in saying ‘the FSA computes the digits of pi’, you can say ‘the rock computes the digits of pi’; it’s precisely the same situation: not knowing the digits of pi beforehand, and only using a physical system, and a table that tells you how to interprete the states of that system (which, for convenience, is often implemented in the form of a monitor for modern-day computing systems; in earlier days, you had things like, e.g., punchcards), you will learn the digits of pi—the outcome of the computation.
Note that we haven’t done anything to the rock but to look at it. If we look at it differently, we can bring out other computations—any computation that an inputless FSA is able to implement (which is any computation a PC, or any finite system, can implement). So if there is now a computation that gives rise to consciousness, then there is a way to look at the rock such that it performs that computation—using nothing but an (extremely large) lookup table taking the rock’s states to the states of the computation.
But if that’s true then it either means that the rock is conscious when looked at in a particular way—which is a strange conclusion: how could the presence of consciousness depend on who’s looking how? Or, the rock should best be taken to perform any computation that can be ‘brought out’ by using the appropriate translation—but then, the rock would have conscious experience, and moreover, all possible conscious experiences simultaneously. Neither seems a palatable conclusion.
And what consciousness does have them? After all, in the earlier discussion, nobody seemed to disagree that there could be beings behaviourally indistinguishable from us, that nevertheless have no conscious experience—formulated differently, beings that have all our inputs and outputs, without consciousness. So those inputs and outputs are in no sense inputs and outpurs of consciousness, as they’re there with or without it.