If subjective experiences are part of a causal link, then a behavioural analysis will eventually have to take account of them.
Sure.
If however subjective experience is not part of a causal link, then it will be possible to make a full behavioural analysis without including subjective experience.
I'm not sure this is coherent. It should be phrased the other way--if a full behavioral analysis is possible, and that analysis does not include something that can rightfully be called "subjective experience", then there's no such thing as a subjective experience.
This is the real problem scenario. If you really do have subjective experiences, then it necessarily follows that the term "subjective experiences" means something; and that requires, as a requisite condition, that we were able to associate that label with some thing. How did we ever manage to do this if there's no causal connection?
Even if a sufficiently detailed analysis does include subjective experience as a necessary part of a causal chain, we certainly don't have access to that causal chain so far.
This directly contradicts your claim that you know you have subjective experiences.
Clearly if subjective experiences are real, and his explanation rests on them not being real, then his theory is not correct.
Suppose we pick up the machine from before, and find a label on it claiming that it was made with Infografix Technology <TM>. "Humbug!", says your robot researcher. "I cannot believe in what is obviously a ploy by a marketing guy to sell this device." And so the robot researcher opens the machine, starts fiddling with it, and then manages to figure out exactly how the machine works.
"Aha!", says the robot researcher. "Just as I suspected. I now have a complete theory of this machine's inner workings, and nowhere did I ever run across this Infografix Technology thing. I knew there was no such thing!"
Now, I suspect the robot researcher is loony. Even knowing the full workings of the machine, there's no way it can conclude that Infografix Technology does not exist, because the robot researcher forgot to figure out what Infografix Technology even means. The robot could easily be wrong, given that the workings of the machine that the robot researcher figured out
is Infografix Technology.
This is not surprising because he lacks information that is possessed by people who do have subjective experiences - i.e. that subjective experiences are real.
Back up a bit. Before telling me that we have information that subjective experiences are real, tell me what it means for them to be real. And before we get there, please tell me how we came to conclude that these were the things we should be attaching the label "subjective experience" to, in order to call ourselves worthy Native English speakers.
In the world of the objective robot, subjective experiences are every bit as unreal as magical elves.
There's only one world though. The objective robot needs to figure out what the words "subjective experience" refer to. Upon opening up our heads, it figures out what causes us to utter those words. Somewhere in that mess is the key to that objective robot understanding what "subjective experience" means.
The next step is for that robot to determine if the thing it discovers "subjective experience" should mean, is actually there.
Given this, I'm not so sure I agree with your conclusions. If we are really describing subjective experiences, then there must be something there that we're talking about. This thing must play a critical causal role in our description of it. And therefore, the robot researcher should find a correlate to the term "subjective experience" and some thing that really is there, causing us to label it with that term. If the robot does not associate the term "subjective experiences" with the mechanism that causes us to describe them at this point (which should necessarily exist, if we have those things), then the robot is broken. Check the warranty.
If he could construct a theory which explained their behaviour - including their claim of subjective experiences - without having to allow for the reality of subjective experiences - then it seems likely that he would do so.
"Without having to allow for the reality" is a bit of a bigger claim than you're letting on. It's more like denying that our star maker uses Infografix Technology. Sure, you can
say that a theory including Infografix Technology would be superfluous, but you cannot actually deny the reality of that theory unless you know what Infografix Technology refers to.
But in our case, your robot researcher should know exactly what causes us to claim we have subjective experiences. That
in itself tells the robot what it is we're referring to.
It is indeed the case that such an objective approach would assume that subjective experience is not real.
No, it's not the case. The subjective reality and the objective reality should be the same reality. You are underestimating what it takes in order to make a claim that a thing is not real.
In order to allow that subjective experience is real he would need to incorporate a number of ill-defined additional concepts into his world model.
He would only have to incorporate a theory concerning the meaning of "subjective knowledge" relative to the entities he is studying. The causal mechanisms are sufficient for him to incorporate that theory.
If we assume that the objective robot has access to the same knowledge we have now, then he might well assume that subjective experience does not exist. We, on the other hand, are very unlikely to assume this, because we know it does.
You're directly contradicting yourself above. If we know subjective experiences exist, and the robot has access to the same knowledge we have know, then the robot automatically knows subjective experiences exist.