You point out that the meaning of words has been brought into question. Yes! I wish that policy makers could understand that.

The search for common ground is the starting point for meaningful dialog. Ernst von Glasersfeld developed an epistemology he calls Radical Constructivism in which he asserts that meaning construction is more a matter of viability than any ‘correct’ interpretation of reality. From this point of view, agreement is attained when our meanings seem compatible, as opposed to everyday standards of truth that imply sameness of interpretation. From his book, Radical Constructivism (p. 182):

…blind faith in the efficacy of language is probably the most frequent impediment to successful teaching…the difficulty is greatly reduced if the teacher keeps in mind that the words he or she uses have, for the listeners, associative links to their own experiential worlds and not to an independently existing reality that would be the same for all.

You reffered to the “death of the Teacher”. Oh dear I hope there is still hope for instruction and transferal of wisdom and instruction. But I agree with your point, that it is the biggest problem facing teachers today.

The very meaning of words and ideas have been brought into question. As Yeats said, the falcon cannot hear the falconer.
So how do you convey an idea if there is no certainty of common ground?

Holistically I suppose. Bounce it around. Debate, argue, fight, disagree, and agree. And hopefully come out on the other side with an increased capacity for critical thinking. I think that is the key.

We have been trained in facts and figures when what we need is the skill to think critically about those figures.

I am not a teacher (yet) so I haven’t faced today’s post-post-modern mind and tried to reach into it. Anyone out there been through that?