Can you change a cats name?

Chelsea • 28 years old! Mommy to an angel baby, and an amazing boy! 😘
So yesterday my boyfriend and I brought home a second cat. He's only about a year and a half old. Maybe not even that old. He doesn't respond or anything when you call him by his name. So I'm just wondering is it weird or I guess 'unethical' to change his name now?