I think it comes down to Occam's razor. There are two equally valid theories: 1. Other humans are sentient, therefore they act like what I would expect sentien

I think it comes down to Occam's razor. There are two equally valid theories: 1. Other humans are sentient, therefore they act like what I would expect sentient beings to act like 2. Other humans (or a subset of them) are not sentient, they are just insanely complex biomachines that mimic acting like what I would expect sentient beings to act like In 1. sentience can be explained as a property common to at least humans, and maybe further as an inherent property of complex machines. In 2. sentience seems to be a property of a subset of humans. Why? What makes sentient beings sentient? Answering this question requires invention of a soul. Theory 1. feels simpler to me.