…and see a tortoise It’s crawling toward you. You reach down and you flip the tortoise over on its back. The tortoise lays on its back, its belly baking in the hot sun, beating its legs trying to turn itself over, but it can’t. Not without your help. But you’re not helping.
See, I’m programmed not to harm tortoises, but they neglected to also program me to not allow tortoises to come to harm through inaction.
So, I was capable of flipping the tortoise over because I knew that I could flip him over again immediately with no harm done. However, once the tortoise was flipped over, I had no obligation to not allow the tortoise to come to harm through inaction on my part. *
Full credit to whatever Asimov short story this was from…something about robots working in an environment with some minor radiation