Hi baywax.
This may be difficult concept to grasp. I have no doubt it is.
Putnam mapping relies on the supervenience thesis. See Stanford Encyclopedia of Philosophy.
http://plato.stanford.edu/entries/supervenience/
I think for the purposes of this thread however, I’ll simply quote Maudlin because he nails it on the head without undo rhetoric:
… two physical systems engaged in precisely the same physical activity through a time will support the same modes of consciousness (if any) through that time.
Ref: Maudlin, “Computation and Consciousness”
So if we have two systems, each of which can be shown to have precisely the same physical activity through some period of time, then those two systems will support the same conscious experience. In fact, they’ll share everything including memory. IFF the two systems mirror each other perfectly, then they should share everything, including experience.
Now the problem with symbols encroaches.
~
What is it to say that physical system A is in some specific state? How do we determine that some physical system is in some physical state A?
Functionalism is a concept that Putnam came up with. He states that essentially, if two physical things provide the same function, then those things can be called equivalent. My apologies to others reading for the brevity of this statement, but I hope it captures the essence.
How do we know if two things are equivalent or not? If I asked if 1+2 = 3 or if A + B = C, you might respond that the first is true, but A+B=C doesn’t make sense because they aren’t numbers.
So if all I needed to do to prove to you that A+B=C is to say that A=1, B=2 and C=3, then obviously you’d have to agree with me.
I obviously wouldn’t have to use A, B and C. I could use any symbol whatsoever. I could use x, y, and z. I could use the temperature at that point. Or the … wait… (Make up your own symbols in your head here. Any will do.)
~
Ok, now we agree that mathematics doesn’t rely on the symbols used. Nor does any computation. We could use the stress at some point in my hypothetical aircraft wing to represent a number. Or we could use the temperature at that point.
or the specific heat of the material
or the emissivity
or the strain
or the thermal conductivity
or the … you fill in the value.
Once you fill in the value. Change it, because it doesn’t matter. All that matters is
- that you used a reference for your symbol.
- And you decided what that symbol meant. (meaning is in your head)
~
Do you realize how much trouble you’re in yet? Yes… we’re in deep doo doo….. <oh poop.>
~
Searle is still active. Putnam however has retired. We’ll miss him. He’s no slouch. Putnam gave us functionalism and just before retirement, he wrote a book that took it away. Bishop is following on.
I talked to Bishop two months ago to better understand all this. Here are my notes:
From phone interview with Bishop, November 19, ’07:
Putnam, Bishop, point out that one can find any given thing (open physical system) in any given state such that the state varies over time from state 1 to 2 to 3, etc… It changes over time because of modal influences on any open system, those modal influences being the influence of the environment on the system. Similarly however, a closed system can be seen to go through some set of states (ie: such as a counting device which goes through 1, 2, 3, etc…). Therefore, the open system can be perhaps better represented by a simple counting device which goes through some arbitrary states 1, 2, 3, etc… with no loss in generality. Note that each state, 1, 2, 3, is a combination of all microstates of the machine.
Secondly, we can look at an FSA as going through or being in various states A, B, C, etc… over some time period t0 to tn. Note here that the states A, B, C are also a combination of all microstates of the machine.
Now one needs only to ‘map’ (Putnam mapping) or compare the open system with the FSA by saying that states 1, 2, 3, etc… correspond to FSA states A, B, C, etc… This mapping is possible because the states 1, 2, 3 and corresponding states A, B, C are symbolic. There is no intrinsic quality to any specific state. (ie: Symbol Grounding Problem per Harnad)
We are now left with the conclusion that:
1 = A
2 = B
3 = C
Etc…
Since this is true, we are left to conclude than any phenomena, such as consciousness, possessed by the FSA must be similarly possessed by the open (or closed) physical system.
There are (at least) 2 counters to this:
1. Counterfactual argument
2. CSA argument
Counterfactual argument holds that this mapping can only be accomplished after we already ‘know’ the states the FSA possesses. However, the FSA also has the ability to transit into different states depending on input, and if it did, the mapping would either be invalid or have to be changed to match the new states of the machine.
The CSA argument per Chalmers points out that if we consider the state of the individual switches instead of lumping all these individual states into a single state such as with an FSA, then the number of additional states quickly becomes extremely large and one can not map a one to one correspondence because of the need to define each of these individual states.
I believe the CSA argument (see Chalmers, “Does a Rock Implement Every Finite-State Automaton”) dismisses the Church Turing thesis since Chalmers is claiming that the CSA is somehow functionally different than the FSA and can therefore support phenomena not had by the FSA. Consider here the FSA=Universal Turing Machine.
~
1. The counterfactual argument just plain sucks. er… sorry for the Vanesh <French>
I also emailed Chalmers about his. Chalmers supports the counterfactual argument:
the idea is roughly that just duplicating I/O from the parts isn't enough to preserve mentality, etc -- you have to duplicate all *potential* I/O too.
That’s a good summary. As good as Maudlin’s summary of the supervenience thesis. Do you think it’s reasonable? Do you think that a machine has to instantiate all possible non-used physical states?
The counter is that counterfactuals don’t count.
See Bishop.
“Counterfactuals cannot Count”
“Dancing with Pixies”
“Mechanical bodies; mythical minds”
See also Maudlin, “Computation and Consciousness”.
~
All this isn’t to say the argument is one sided. Christley for example, uses a very similar argument to your argument about the mirror. Christley states:
Furthermore, consider an animated display of a Turing Machine on a computer screen. Since, ex hypothesi, there is a one-to-one correspondence between the states of the display screen and the states of some Turing Machine, Searle and Putnam would apparently claim that the screen realizes the Turing Machine, if anything does. But it seems clear that we would say that the screen depicts a Turing Machine, but is not itself one. One reason why we would deny it computational status is because the state of the screen that corresponds, in the putative interpretation function, to a computational state A does not produce, as a causal effect, the screen state that corresponds to the successor computational state B, even though the Turing Machine depicted does make a transition from state A to state B. Computational states must be able to cause other computational states to come about.
Ref: Christley, ‘Why Everything Doesn’t Realize Every Computation’,
Christley doesn’t deny that the screen instantiates the physical state. He’s saying in affect, that the screen can’t support counterfactuals. However, I have to disagree that counterfactuals are necessary for any consciousness. This requires spooky, nonlocal causal actions.
~
It took me about a year to understand this and come to some agreement with any of it. I think we need to try and understand what’s being said before we cast judgment. I can’t for the life of me, see anyone grasp all the nuances here reading this over once. It’s difficult to grasp as it’s a very abstract argument that needs some basis on cold hard physical law to become clear. So before saying that x doesn’t mean y or creating any argument based on what you read here, I only ask that what you don’t understand… ask. No one is going to understand the arguments provided by people like Chalmers, Christley, Putnam, Bishop and others the first time through.
