Self-paced
Zachary: The term "fresco" refers to paint that has been applied to wet plaster. ████ ██████ █ ██████ █████████ █████████ ███ █████ ████ █ ███████ ███ ███████ ██ ████ ████ ██████████████ █████████ █████ ██ ████ ████ ████ ██ █████ ████████ ████ ████████ ███ ████████ ██████ ████ ████ ██ ████████████ ██ ███ ███████ ███████ ██████████ ██ █████ ██ ███████ ██████████████ ███████ ██████ █████████ ██ ███ ██████████ ████ ████████████ ████████ ████ ██ █████ ██████████ ██████ ███ ████████ ██████ ████ ████ ██ ████████ █████
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Stimulus Summary
Zachary lays out some background and then a recommendation. A fresco is paint applied to wet plaster, and once it dries it permanently locks in the paint the painter used. In the Sistine Chapel, later painters added work that now covers up Michelangelo's original fresco. From this, Zachary concludes that to return the chapel to the appearance Michelangelo intended, everything except the original fresco work has to be stripped away.
Notice that Zachary treats "Michelangelo's original fresco work" and "the appearance Michelangelo intended" as the same thing. That makes sense only if Michelangelo wanted nothing on the wall beyond the original wet-plaster painting.
Stephen points out that painters of Michelangelo's era commonly went back and added painted details to their own frescos after the plaster had dried. His implicit suggestion is that, if that was common practice, Michelangelo may well have added his own details after the fresco dried, and those additions could be part of the look he intended. Stripping everything down to the bare fresco could then remove some of Michelangelo's own intended work.
25.
Stephen's response to Zachary proceeds ██
a
calling into question ██ ██████████ ██ █████ █████████ ██████████ ███████
This describes what Stephen does. Zachary's conclusion depends on the unstated assumption that Michelangelo intended only the original fresco and added nothing after the plaster dried. Stephen's fact about common practice goes straight at that assumption, raising the possibility that Michelangelo made his own later additions, which could be part of the appearance he intended.
b
challenging the definition ██ █ ███ ████ ██ █████████ ████████
Stephen never disputes the meaning of any term. He accepts Zachary's definition of fresco as paint on wet plaster and works within it. His point is about what painters of the era commonly did, not about what counts as fresco, so there is no challenge to a definition here.
c
drawing a conclusion █████ ████ ███ ███ ████ ███████ ███████
Stephen does not state a conclusion of his own. He offers a single fact, that adding details after drying was common, and lets it undercut Zachary's reasoning without spelling out where it leads. He never asserts, for instance, that the later work should be kept.
d
denying the truth ██ ███ ██ ███ ██████ ████████ ██ █████████ ████████
Stephen does not deny any of Zachary's stated premises. He accepts that fresco locks in the paint and that later painters obscured Michelangelo's original work. His fact about common practice adds to the picture rather than contradicting anything Zachary actually said. This is the key distinction: Stephen targets an unstated assumption, not a stated premise.
e
demonstrating that Zachary's ██████████ ██ ███ ██████████ ████ ███ ████████ ██ ████ ██ ███████ ██
Stephen does not show Zachary contradicting himself. Zachary's premises and his conclusion do not go against each other; the problem with Zachary's argument is only that getting from one to the other needs an extra assumption.