The biggest contradictory moment always seemed to me to be when they're all arguing over whether or not to give the giants a bloody nose (I think?). Spock says he's often appalled at the low regard Earth men have for life. A human being then says
"At least we're practical about it!"
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Now, that seemed unintentionally contradictory to me, for decades. Now, though, it seems to me to be the pivotal moment, as far as its overall message. The hypocrisy of that, the 180 degree turnabout on the part of the human crewman, there's where the truth comes out. The humans had been riding Spock for being callous and calculating, and getting them killed, as a result of not empathizing with and protecting them enough. He doesn't feel like we decent folk do, supposedly.
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Then what's-his-name shoots off his mouth about how they've got to kill just to scare the aliens off. Suddenly Spock's the bleeding heart, and it's the good old, right-minded human who doesn't let sentiment get in the way, and is "practical" about death.
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