Language is not supernatural

Nicolas! So you knew that I knew that you were setting a trap. But did you know that I knew that you knew?! ;-)

I did not define "complete" to mean that the proposition must be written in a way that is comprehensible to someone in a completely different language. If I say that "the acceleration of an object is inversely proportional to its mass", a man who knows only Japanese will not understand any of my words or verbs. This does not render my proposition meaningless or untestable. Similarly, a claim that "neutrino mixing is responsible for the deficit of solar neutrinos" is no less complete just because you have not learned how to interpret it. The fact is that you can learn to interpret it and perform the experiments that will falsify the proposition.

From my perspective, your counterclaim is trivial. It basically says that in order to understand a proposition it must be expressed in a language you have learned.

I have a problem with the linguistic school (Wittgenstein et al). They mistake language for something more fundamental than a protocol.

First, I would answer by saying that perception of the world does not require language. Other species (and a few individual humans) have demonstrated the ability to perceive the world and even use tools without using language at all.

Second, scientific progress in neuroscience, language and information theory have made the linguistic school obsolete. If language was fundamentally linked to perception and understanding of the world, it would be invulnerable to scientific explanation. However, it is straightforward to see how language works from a scientific perspective. With science, we can gauge the limitations of our language.

There's a good analogy here. Science accepts that a universe that is subject to physical laws is perfectly compatible with the fact that experimental measurements have finite precision. Similarly, we can say that conceptual representation of the world (meaning) is perfectly compatible with language that has finite precision. In both cases, we can make propositions about the world with an arbitrarily high degree of precision, and falsify those propositions to a correspondingly high degree of precision.

Language is simply a technology for communication. It is not beyond science, and it is not metaphysical.

doctor(logic)