Pronoun dilemma

The passage below is from “Justice, what’s the right thing to do.”

The problem is I’m not so sure about what the underlined ‘it’ represents.
It seems to mean ‘our conviction’ in one way, but also ‘the reason’ in another.

Can you help me?

http://www.kpug.kr/kpugfreeboard/681056

One way to begin is to notice how moral reflection emerges naturally from an encounter with a hard moral question. We start with an opinion, or a conviction, about the right thing to do: “Turn the trolley onto the side track.”

Then we reflect on the reason for our conviction, and seek out the principle on which it is based: “Better to sacrifice one life to avoid the death of many.”