First, we would have to say that there is a correct response, one which is according to the rule, because simple response is insufficient to demonstrate the existence of a rule. — Metaphysician Undercover
If you fetch a red apple whenever you are asked to then you know the rule. It is as simple as that. Fetching the apple is sufficient. What more do you think needs to be added? What is missing? Whether or not one is following the rule is determined by an action:
“We could imagine that the language of §2 was the whole language of A and B; even the whole language of a tribe. The children are brought up to perform these actions, to use these words as they do so, and to react in this way to the words of others.” (§6)
So in this sense, memory would be the "highest court" because it determines whether something has meaning or not. — Metaphysician Undercover
The paradigm is the highest court.
"An example of something corresponding to the name, and without which it would have no meaning, is a paradigm that is used in connexion with the name in the language-game." (§55)
A physical example is in general a more reliable paradigm provided it does not change. In addition, we are able to compare the sample with the name. I do not need to consult a sample of the color red each time I fetch a red apple, but if you fetch a yellow apple and say that this is how you remember the color red, then we can consult the sample to settle the matter of what red means.
Also, it suggests that meaning is not indestructible as was earlier suggested, because when the memory is gone, so is the meaning. — Metaphysician Undercover
I may forget what red means, but there are still samples or examples that serve as the paradigm. The physical sample is not indestructible but more durable and reliable than a memory. It would only be the case that red had no meaning if there were no paradigm, either physical or mental, that connected the name to the color.