The epics have both kinds of arguments on ahimsa. Shukracharya once told the asuras that ahimsa was the biggest dharma. Even if someone approached with an intention to kill, a person should not use violence. That would be himsa, as per Devibhagavata Chaturskanda. But as per Mahabharata Aranyaparva Chapter 208 verses 32-33, the sage Markandeya has asked who in this world could live without consuming some life or the other.