"We can't afford to play it safe anymore, Raven. We're on the edge of survival here. Yesterday we only had to concern ourselves with walking zombies and oversized animals. Today, we faced three evolved zombies, while the rest were all able to run. What about tomorrow? Or the day after?"
As Raven imagined their base being overrun by hundreds of evolved zombies, her stance began to falter.
"We are evolving," Levi continued. "So are they. We need every advantage we can get. You may believe you are doing the right thing, but you are only delaying the deaths of everyone here if we don't use this knowledge to become stronger. Strength in this world has become more valuable than our morality."