Visual arguments are indeed arguments, but they don’t work in the same ways that verbal/textual arguments work (in fact, I would argue that not all verbal arguments work the same way, either). Arguments do put forth premises, and they do have a grammar of how they are constructed, with major, minor premises, a hierarchy of evidence and support, a misuse of these elements to create fallacies, etc. More than words, I think, visual arguments have the viscerality that Gibson discusses, the kind of gut reactions that are then justified with logic afterwards.
I looked at Laurie’s, Jenny’s, Dan Cox’s, Megan’s, and Chvonne’s arguments. Megan and Donovan commented on mine. While my intention in the argument I thought I was conveying in the composed photo was closer to what Megan wrote, Donovan’s interpretation is not incorrect. I would say that it is more like Megan’s is my major premise and Donovan’s is my minor premise. My argument was one of girl power, and also one of familial love. The princess tropes are more “typical” femininity, while my daughter and I are dressed as female superheroes and “mutants.” We stood together in solidarity, back to back, united, deliberately in the same pose as Elsa and Anna to create the juxtaposition. Of course we are “real” and they are cardboard cutouts, but we are also not fully ourselves as we are cosplaying Storm and Black Widow.
I believe visual argumentation exists, and that the logic of design and placement and argumentation can be decoded and conveyed. Just like with text, however, there will be some who don’t “get it” and there will always be the variance of reader response. That variance exists whether with words or images, as arguments are layered and nuanced and audience members are diverse. Just because an argument is decoded that the designer did not intend does not negate the concept of presenting an argument. But just as an author must consider all the meanings of a word or phrase, as well as of the sentence, paragraph, and the whole, a designer must consider all the meanings and implications of design choices. As Stuart Hall notes, there will always be difference in the encoding/decoding as a result of individual and ideological particularities as a result of lived experience.