1 Introduction
Here Las Casas’ intent as historian and scholar is straightforwardly polemical.
He tells us who’s on the other side of the dispute, right up front; see p. 1.
And in green Las Casas’ own broad overview; again see p. 1.
2 Religious belief
See the argument on pp. 1–2, whose purpose and meaning should be familiar to you. And note the subsidiary justification in green on p. 2.
3 Government
One of the fundamental questions Las Casas and Sepulveda see themselves as being posed is whether the indigenous people are capable of self-rule. This is, more or less, the Aristotelian standard: Some people, on the Aristotelian view, lack the kind of foresight critical to the formation of political community; they are his ‘natural slaves’.
Las Casas’ argument on p. 3 is more or less an empirical one, but it is interestingly staged, as it were. His argument is partly that indigenous people have, demonstrably, the capacity for self-government, but one ingredient of this capacity is their natural situation. In a sense, this vision (not entirely an exclusively modern one) persists right through Rousseau into the present: that differences between humans cannot be accounted for entirely in terms of character or internal constitution; terrain, setting, geography must have some role to play in the makeup of culture.
4 Relativism
One of the inevitable consequences of the colonial experience is questioning the ‘necessity’ of culture. (The later career, in the nineteenth century, of the concepts of civilization and then of civilizations is instructive.)
Consider the yellow passage on p. 4.
And some inverse characterizations hold also; see the green passage on p. 4.
See the punchline of all this on p. 7.