Applying Peirce to Image Interpretation --- Part One

The basic notion of Charles Sanders Peirce's, that the positing of an abduced structure of some sort (e.g. a Schankian script in a Davidsonian representation world) can organize a set of disparate pieces into an explanation, is sound. The problem is how to play that through for the specific case of, say, Albrecht Altdorfer's Alexanderschlacht.

The start of the story must be the flags and the labels, because they give specifics. We also need to hold the inscription aside, because there is a strong suspicion that it is not by Altdorfer himself, but later (possibly by Jean De Pay in 1658, whose restauration receipt is already mentioned by Franz von Reber's Catalogue of the Old Pinakothek's collection of 1900 in the 8th edition, though Buchner in the 1938 Katalog for the 400th anniversary exhibition in Munich seems first to suggest that this included a reworking of that inscription).

There is a list of possible sources that Altdorfer could have used for obtaining the details of the battle. That list includes Arrianus, Quintus Curtius Rufus, Justin's Epitome of Trogus, Aventinus, the Alexander Romance of Johannes Hartlieb, Schedel's Nuremberg Chronicle, and Plutarch. (For some of Aventinus' views on this matter, see this post here.)

Per CSP's recommendation, we can now construct alternate worlds of various forms. The basic idea would be that Altdorfer used exactly one source. For example, as Cord Meckseper did in his article on the iconography of the battle (Zeitschrift des Deutschen Vereins für Kunstwissenschaft, XXIII, 3/4, 1968, 178-185), one might assume that Schedel's Weltchronik might suffice.

The point is to expand what »suffice« might mean in terms of a strategy of mechanical interpretation. We assume that the narrative (it is not very long in Schedel) is summarized in a suitable Davidsonian event representation. This instantiation then identifies actors, actions, matériel and similar.
We also need a similar instantiation of the content of the painting itself, as an event, describing the various discernibles. Here, we can simplify the problem by delineating (e.g. with TEI standard bounding boxes) and describing at the action level (moving, turning, etc.) all those entities that any of the art historic works we have considered have identified, i.e. the superset of the interpretation constituents. Recall that we wish to model the argumentation, not automate the argumentation.

But if we have the description of the picture, and the description of the events as reported in the various sources, what then is the abduction doing for us? It is the mapping between these components, a representational correspondence. The picture has a golden-armored man riding a white horse. The story has Alexander leading a charge (say, not all sources go into that detail). The abduced mapping then says that the man on the white horse is Alexander (and by one step of inference that leads us beyond the sources, the horse is Bukephalos).

Consider the battle flag for a moment, which consist of the following pieces of information:

• the army to which the troops are attached (Greek/Macedonian or Persian, often mentioned pars pro toto via the commanders Alexander and Darius III)
• the type of troops we are talking about (here, mostly foot vs horse, i.e. infantry vs cavalry)
• the number of men present at the beginning
• the cardinalities of the categories at the end of the battle
• killed (presumably this includes missing in action, in modern parlance)
• captured (e.g. 40k Persians in Justin and Schedel)
• escaped (1k horse w/ Darius in Quintus Curtius Rufus, 4k in Arrian)

Here we are matching not against actors or roles in the script, we are matching against event statistics, so to speak, or statistics of sub-events (e.g. the troop numbers at the beginning and at the end of the battle). The flags visually represent the battle statistics (which are abstractions and therefore not visible per se).

In all of these representational mappings, we can run into four situations:

• NONE: there is something in the image that is in none of the sources (the scythes on the fleeing chariot, the chariot driver felled by the arrow, the boats on the sea), 
• ALL: there is something in the image that is in all of the sources (Alexander, Darius)
• UNIQUE: there is something in the image that is only one of the sources (the women, Oxarthes)
• SHARED: there is something that is in some, but not all of sources (the 32,000 Macedonian foot in Aventinus, Justin's Epitome of Trogus and Schedel's Weltchronik)

We have different reactions to these situations, then, as they give us different information about the question of which sources were used.

• NONE means that Altdorfer invented the matter himself
• ALL means that we cannot distinguish between the different source theories based on this piece of information
• UNIQUE means that the specific source was definitely used

SHARED has a special status, as it is often an indication of the genealogy of the sources themselves. For example, Altdorfer was not the only one working from sources, both Aventinus and Schedel had to use ancient reports to underpin their reconstructions. We may not be able to separate out Justin from Trogus, since Trogus did not survive the ravages of time as an independent source. But since Justin  (200-400 AD) is temporally before Schedel (1493) and Aventinus (1526), it is likely that Schedel used Justin (in the particular case of the 32k Macedonian foot). There are other cases were Schedel agrees with Justin, such as the number of 40k captured Persians.

The problem is trickier in the case of Aventinus, whose Bavarian Chronicle was published in 1526 when Aventinus was already living in Regensburg. Since Schedel predates Aventinus by over 30 years, and Aventinus only discusses Quintus Curtius Rufus as well as Arrian (Bk I, Cpt 153, p.337), as well as disparaging Hartliebs Romance. So perhaps Aventinus used Schedel and not Justin; unfortunately he mentions neither.

One more point about the NONE category, because Alexander's horse Bukephalos falls into it. None of the source I have looked at specifically mention that Alexander was riding Bukephalos at the battle of Issos. But Bukephalos is not invented in the same way that the chariot driver pierced by the arrow is, and not in the same way that the scythes on the carriage are. So we will have to return to the problem of this category at a later point.

But before that, we have to look at the problem of dealing with the open-ended disjunctions.