The point of departure . . . is whether the Indians were true masters of their possessions and institutions before the arrival of the Spanish. That is to say, if the Indians didn't have a legitimate right over their lands, the Spanish could take them without asking. To this Vitoria [Franciso de Vitoria, a Dominican monk] responds that the Indians certainly were legitimate masters. Neither mortal sin, nor idolatry, nor the supposed lack of mental capacity are sufficient to negate right of possession . . . . the right of discovery, is also illegitimate, such that if the Indians were true masters of their lands . . . those territories weren't there waiting to be discovered, as if we were talking about a deserted island.1This second quote makes me think about what we might be overlooking today...
The great tragedy of the conquest wasn't that a crowd of heartless Spanairds spilled over the American continent, but that those who arrived in these lands were sincere Christians who in spite of this did not appear capable of seeing the relationship between their faith and that which was happening in their days. This is true, not only of Colombus and many descubridores, but also of the conquistadores like Cortés and Pizarro, who saw their business as a great service dedicated to the preaching of the gospel. And so the tragedy was that with all sincerity and in the name of Christ the most horrendous crimes were commited.1
1 J González, Historia del Cristianismo, Tomo II (Colombia: Unilit, 1994, translation mine)