The idea that meaning consists of associations is extremely primitive. It works for concrete nouns and verbs but it quickly fails as things get more complex. Language is used to refer to refer to abstract things, imaginary things, counterfactual situations, etc. And even if you do arrive at a series of concepts using associations, you have to understand how they are supposed to combine, even for completely novel sentences. In all these cases, there's arguably nothing there to associate with. I can't answer your question (I think no one can), but we can conclude that meaning is more than associations.
Isn't that Chomsky's argument here (in this article, not in his approach to linguistics in general)? -- That it is a good idea to try to find a better understanding of how the internal mechanisms work so we can build or simulate it better. You do that with carefully constructed experiments not with just observing inputs and outputs and training a neural network or a Markov model with it.
Please argue that there is nothing to associate with.
Why is a real observation from your senses more privileged inside your brain that a random well-formed value by a (hypothetical) random number generator neuron?
I argued that if you only have associations with previous experiences, you won't be able to deal with novel input. Ergo, you need more than just associations (synthesis, imagination, counterfactual reasoning, etc.).
As to your second question, I don't see how it relates to my argument, but I'll answer anyway. If you're comparing a observation to a random number, you're looking at the observation qua value, in which case it has the same status. If, however, you look at the level of interpretation (what it means in your brain), the observation has a complex set of relations with the rest of your brain and gives rise to a perception, wheres the random number value is just noise that has to be tolerated by the brain.
