At the session on Epistemic Relativism, Paul Boghossian was comparing epistemic and/or ethical relativism to a relativism that might be more palatable; relativism about motion. This post is about 'motion' talk, itself.

Basically, since modern science tells us that no motion is absolute, and the only applicable concept of motion is motion relative to some reference frame.

At one point, Boghossian was discussing what to say, once we've concluded how 'motion' talk works now, about what was going on with speakers before we discovered the relativity of motion.

One option discussed was that they were attributing some non-existent absolute motion property and were just wrong all the time. Another was that they were slyly and unawaredly doing whatever we do now. It is from this option that I came up with the title of the post. Retconning is something done in comic books wherein the history of the fiction is revised by current developments in the plot (and similar phenomena).

At first glance, something seems somewhat worrisome about a modern scientific discovery altering the semantics of, say, dead languages. However, to be fair, someone endorsing such a view would almost certainly think that languages have been this way all along and that fact about language is something that we only put together after this scientific discovery. Also, I think that, if one endorses semantic externalism for other reasons, that could reduce worries about this.