The virtuous circle of causation and compassion
What Wright does, which is cool, is to flip the relationship between seeing causation and feeling empathy around: once we start empathizing with people, we are better able to see and accept that there is a causal story behind their behavior (“Thus does love lead to truth”). We’re less likely to cut short our explanations by blaming the supposedly self-caused agent. And, he says, once we see the genetic contingency of our special love for our immediate family, we might be able to expand our circle of empathy, and therefore of causal understanding. This in turn (I extrapolate here) will lead to more empathy as explained above. A nice virtuous circle.
Of course as he points out, some people tend to get depressed by the Darwinian "selfish gene" explanation for familial love, thinking such love isn't real. But to explain isn’t to destroy, only explain. Unless, that is, you’re wedded to dualism and think it’s the case that the soul or something immaterial is essential for anything valuable. Which would be too bad, since the physical world has cooked up some pretty amazing and sometimes even loveable phenomena.