Engineer: Support Semiplaning monohulls are a new kind of ship that can attain twice the speed of conventional ships. ███ ██ █████████ ████ ██████ ██████████████ ████ ██ ████ ████ █████████ ██ ███████████ █████████ ████ ██ ████████████ ██████ ██████████ ██████ ██ ███ █████████ ███ ████ █████████ ████ ██████ ██ █████ ██████ ██ ██████ ███ ███ █████████ █████ █████████ ██████ ██████████ ██ ██ ███████████ ███████ ████ ███████ ███████ █████ ███ ████████████ ███████████ █████████ █████ ███ ████ ██████████ ████ ███████████ ██████ ████ ████ ████ ████████ ██ ██████████ ██ █████
The engineer's argument breaks into four moves:
1. Premise: Semiplaning monohulls are twice as fast as conventional ships.
2. Concession (this is the referenced text): But monohulls are more expensive than conventional ships, because they burn more fuel.
3. Analogy: Jet airplanes had the same setup: more expensive than other planes at first, but still profitable because of their greater speed and reliability. Monohulls have those same advantages over traditional ships.
4. Conclusion. Therefore, monohulls will probably be profitable.
The engineer raises the increased-expense point as a concession because she knows it looks like a problem for her conclusion about monohulls' future profitability. She then uses the jet airplane analogy to respond to that concession.
Standing alone, the referenced text cuts against the conclusion. Saying something is more expensive doesn't help the case for profitability; it hurts it. So the referenced text isn't a premise that supports the conclusion.
The engineer raises it anyway, then handles it with the jet airplane analogy: jet planes were also more expensive at first and were profitable anyway, so the same outcome is plausible for monohulls.
So the role is: a concession the engineer makes, but responds to with an analogy.
Analysis by Kevin_Lin
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