Trolls are slow in the uptake, and mighty suspicious about anything new to them.
When Bilbo and the dwarves encounter a group of trolls, the narrator describes the nature of trolls as a race. The characteristics of the different races are central to the way Tolkien defines this story’s world—and in that world, wide racial generalizations tend to bear out as true. This generalizing, though mostly used for world-building and the establishment of tensions and conflicts, does slightly complicate the message about characters being more than just their outward characteristics.
[H]e shook his head; for if he did not altogether approve of dwarves and their love of gold, he hated dragons and their cruel wickedness.
Here, Elrond decides he will help one group, dwarves, reclaim their gold mainly out of dislike for another group, dragons. Tolkien often defines the races by their moral quality, and his characters do the same, resulting in a slightly simplistic, almost mathematical approach to conflicts and alliances. Elrond weighs the two sides, determines dragons to be morally worse based on his impressions of the overall species, and chooses to side with their enemies, the dwarves. This firm racial structure functions as a crucial factor in the thinking of even the most high-minded characters in this world, like Elrond and Gandalf.
Now goblins are cruel, wicked, and bad-hearted. They make no beautiful things, but they make many clever ones. They can tunnel and mine as well as any but the most skilled dwarves, when they take the trouble, though they are usually untidy and dirty.
Here, the narrator gives the reader an overall impression of goblins. Readers may note that even when the narrator acknowledges potentially admirable qualities, the sense of race-based morality remains firm. This world has little room for ambiguity. Though the goblins are, according to Tolkien, clever, resourceful, and skilled, they are still flatly wicked, and Tolkien, as the narrator, presents these observations as objective fact. Though these characterizations seem simplistic, the story gains a mythic quality from this simplicity, evoking ancient epics, odysseys, and creation myths of good vanquishing evil.
I shall think more kindly of dwarves after this. Killed the Great Goblin, killed the Great Goblin!
Here, the bear-man Beorn declares that Thorin and the dwarves’ accomplishments have changed his impression of their whole race. This change of heart illustrates an interesting subjectivity to each race’s moral standing. The characters all have their own thoughts on the other races, based on personal experience, and those thoughts likely differ greatly from character to character. However, when Tolkien as narrator describes the races to the reader, the descriptions are omniscient and objective. The extent of ambiguity’s existence in this world remains elusive.
This is the plan that he made in council with the Elvenking and with Bard; and with Dain, for the dwarf-lord now joined them: the Goblins were the foes of all, and at their coming all other quarrels were forgotten.
The narrator explains that when an army of goblins arrive looking to plunder Thorin’s gold, all the previously warring factions of men, elves, and dwarves find unity and camaraderie in their distaste for the goblins. Race here provides a basis for collaboration and resolution, though only through the establishment of shared conflict with another race. The web of alliances and rivalries between the races in Middle Earth makes the idea of widespread peace unlikely. Though Tolkien does show moral fortitude winning out over evil, he also suggests that evil will never be fully vanquished, and he uses racial conflict to demonstrate this idea.