AJ,
I can’t disallow that you might be able to think abstractly sans language but I would be curious if you might be able to confirm it as a surety over a mere belief. I’ve tried many times, sitting in sensory deprivation I try to think about some abstract idea and chase the demon words out of my head, always in total failure. Then in a rest period I can conjure up the images of a complex mechanism or the construction of a house, and all very relaxed and peaceful, kind of natural, with no words involved.
(It may be like multi-tasking. There is no way that I can do it and so am naturally skeptical about the claims that a few of my friends (all women) have made. Yet clinical testing that has been done shows no gender bias and that generally the ability gets better with practice. But do people actually think about two unrelated things simultaneously or do they merely alternate their attention? I see it as analogous to predators having their eyes on the front of their head focusing intently only on the hunt vs the prey with the eyes on the side of its head looking in many directions at once. But that’s a tangent)
"We interpret every utterance into some form of non-verbal mental experience,* and insofar as we have not yet converted it to non-verbal mental experience, we have not yet actually interpreted it."
"non-verbal mental experience" I would interpret as sensory experience of the real world (even as an after-glow), something that all creatures experience. Abstract mental experiences are “pulled away” from the real, sensual, experiential world. Based on that caveat I absolutely agree that “We interpret every utterance into some form of non-verbal mental experience.” All of language, and abstract ideas, are understood by analogy to the sensual, or experiential, world. The sensual world is the common-ground for all creatures. All language is metaphor, and by lucky coincidence these metaphors are intrinsic in the words themselves, i.e. the etymological roots.
And the coincidence increases as it was about 50,000 years ago that archaeologist find the first evidence of abstract thinking and the proliferation of languages. It was, some might argue, the birth of humanness over and above the mere beast. The two are inseparable; language (vocabulary and syntax) is an abstraction (something pulled away from the sensory experience of the real world) and abstract thinking requires language. The chronological order is that the neologism was birthed upon a metaphor in an attempt to understand something abstract, i.e. something that can not be directly described by sensory experience of the real world. It seems that you would take the word as an existential fact of unknown origin that requires a hearer constructed analogy to a sensory experience of the real world in order to give it meaning.
That most people forget the original metaphors and create their own idioms (lost convention) is the cause of misunderstanding that the OP, Jargon, laments. Yet his observation that individuals would think more clearly about abstract ideas when they refrain from putting them into words is absolutely wrong. Seeking to clearly define abstract thoughts in precise language, as you have done here, is the foundation of understanding. And dialog fleshes out the precise understandings, debate is the crucible where truth is formed. Einstein once said that if you can’t explain it to the barmaid then you probably don’t understand it yourself.