Second session: Leo Groarke's "Saying 'Not' with Images."  Groarke argued via a very nice set of examples that images can indeed express negation.  Classic example: a crossed out hanger (a pro choice symbol).  Paul van den Hoven raised an interesting point in his commentary, namely whether Groarke has shown rather that images can express refutation, rather than "negation."  This raises the broader question about the verbal dependency of visual arguments; or the visual dependency of verbal arguments.

On this score: cf. the "your argument is invalid" meme.