I assert it is wrong to walk up to a stranger who has done you no harm and stab him. I assert it is wrong to take another person's property against her will.
If you need these things to be proven, you are out of luck. I can not "prove" these assertions in the same way a physicist can "prove" his hypothesis or a mathematician can "prove" his theorem. Now, that doesn't mean some philosopher hasn't formulated some incomprehensible mess that his followers hail as "proof", just that, even if he has, I don't feel like chasing it down. I don't need to.
I certainly don't depend upon consensus to show me that my assertions are correct. I know they are. Maybe it is encoded in my DNA. I suspect if it weren't, humans would have been extinct long ago. I also suspect that anyone who doubts these assertions does so for less than "nice" reasons.
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