“We are intelligent creatures! What justifies your behavior?” The appointed spokesperson for the human-slaves of Vega 3 spoke with indignation.

“We are more intelligent. Do you not enslave cattle for your own purposes?”

“Cattle are not sentient. We are!”

“You think sentience is a binary state? I say it is a matter of degree! I am more self-aware than you, therefore I am entitled to enslave you and your entire human race!”

“Either you are sentient, or you are not!”

“Indeed? Describe your self-awareness. To what do you attribute your consciousness?”

The human thought for a moment. “A popular human metaphor for self-awareness is the presence of a person, another me, inside my brain, controlling my actions. It is this metaphorical man-inside-my-brain that gives rise to consciousness and awareness. A cow entertains no such thoughts about its own consciousness.”

“Ah, but what if I were to tell you that I also have a Xilidor inside my brain?”

“Then that would put us on equal ground, and your treatment of us is unjustified!”

“And what if I were to tell you that the Xilidor inside my brain has another Xilidor inside its brain, controlling its actions?”

“Yes, but…” The human stopped short. “Drat! I guess you got me there.”