Rationally, there is no difference what-so-ever between your ability to assess how another human feels pain, and how the robot feels pain (or any other "life" form in between). In all cases, you can only observe behavioral responses to stimuli and make conclusions based on that. Therefor, everyone (else) "feels" "pain" equally as far as you can tell.
There are 2 differences to speak of but they still don't change the above statement imo:
1. You have knowledge of the experience of pain within yourself. You then extrapolate that other people probably have the same internal experiences because they look like you and their external behavior matches your external behavior. But of course, that is just a thought and cannot be proven. Maybe some people feel pain differently to you or not at all (like the idea of "is my blue the same as your blue")
2. The robot was programmed but the nervous system wasn't. Therefor one might say, we know the robot doesn't feel anything but at least I know that I do. If you don't believe in a divine element of being, then a brain is itself merely a computer in the broad sense of being 100% governed by the same laws of physics as a CPU (and everything else). So any experience or behavioral response in you or anybody/thing else has a physical casual link to the stimuli (with a quantum RNG in the mix).
Therefor I'd say that rationally, every feeling of pain, is equally valid, even if it's a program. But we have decided, for emotional and practical reasons, to give more validity to the pain of some creatures than others on an almost continuous scale.
There are 2 differences to speak of but they still don't change the above statement imo: 1. You have knowledge of the experience of pain within yourself. You then extrapolate that other people probably have the same internal experiences because they look like you and their external behavior matches your external behavior. But of course, that is just a thought and cannot be proven. Maybe some people feel pain differently to you or not at all (like the idea of "is my blue the same as your blue")
2. The robot was programmed but the nervous system wasn't. Therefor one might say, we know the robot doesn't feel anything but at least I know that I do. If you don't believe in a divine element of being, then a brain is itself merely a computer in the broad sense of being 100% governed by the same laws of physics as a CPU (and everything else). So any experience or behavioral response in you or anybody/thing else has a physical casual link to the stimuli (with a quantum RNG in the mix).
Therefor I'd say that rationally, every feeling of pain, is equally valid, even if it's a program. But we have decided, for emotional and practical reasons, to give more validity to the pain of some creatures than others on an almost continuous scale.