Regarding the social nature of man, a realistic or productive theory of language cannot be developed that doesn’t include human interaction. Any such theory rests on private language arguments where, even if a code were developed within the mind, it is by nature inaccessible to any other mind and therefore indecipherable. With regards to memory, the reason language helps aid in recall is because of the iterability of signs. The continual convergence of passing theories gives rise to normative linguistic practices as a result of learned conditioning. The repeatability of a word allows for a reliability of an expected usage to emerge and a convention to persist that provides words with their semantic force during a conversation. The conditioning of language is no different than any other form of conditioning. By performing an action and monitoring a reaction we become conditioned to a predictable sense of the relationship between the two. It doesn’t seem that a private language would necessarily develop as a corollary.
In fact, I’d almost say that memories (the ability to recall past impressions that results from conditioning or habituation) can be just as harmful as they are helpful. If the repeatability of words is the conditioning force that anchors meaning into the memory, and if we think in words, then these words can seriously distort a clear perception of reality. If our operating system, our belief system behind our world view, is inured with meaning constructed from words and thoughts conditioned from the past, then we are left with a clouded perception of the present. We exist within a world representative of the distorted figments of past impressions that do not represent a lucid state of being possessed in the now. Our inner world manifests an illusory outer world through a bundle of habits perpetuating memories of fictional meaning that pull the mind into the oblivious past. The memories constructed from our language possess the pervading ideology that manifests as our identity through every psychological and physiological action.