Until recently, experts have been unable to identify the artist who created a Renaissance painting depicting aristocrats in a historic battle.
Conclusion
The artist who painted the self-portrait also painted the battle scene.
Evidence
One of the figures in the battle scene closely resembles the young man in the self-portrait.
Evaluate
This argument springs from a Curious Fact / Explanation template: Curious Fact: who painted this battle scene? Author's Explanation: it's this self-portrait dude.
We want to ask ourselves - is there some OTHER EXPLANATION for the curious fact? - how plausible is the AUTHOR'S EXPLANATION that this self-portrait dude did it?
There aren't really any other causal possibilities teased here, so it's hard to think about proposing an alternate person who could have painted it. However, we could certainly come up with other explanations for the similarity between the self-portrait and the guy in the battle scene: - the dude is just an average looking white guy with a beard, so a lot people of his era closely resembled him - maybe the battle scene portrait came first, and the painter got so entranced by this one figure in the battle scene that he decided to pattern his own haircut and facial hair after him, prior to painting the self-portrait - someone who is friends with the self-portrait dude decided to paint him in the battle scene
How could we make it the author's story sound less plausible? - we could say that the self-portrait artists was only known for painting portraits (hence painting a battle scene wouldn't likely be in his oeuvre). - ? ?
Goal
Look for an answer that suggests an alternate explanation for who painted the battle scene, an alternate explanation for the similarity between the self-portrait and the dude in the battle scene, or a fact that makes it less likely that the self-portrait artist painted the battle scene.