>>If my similarities to you in both physicality and reaction are not enough to convince you I feel pain, why are my words enough? And if they are, if I build a deep belief network which says "ouch, fuck" every time it encounters a penalty in its stimuli and says "awesome" every time it maximizes its reward function, does it follow that we now have to treat it as if it's human?
>Well, since humans are conscious and are able to communicate with each other clearly, we can tell pretty well what it means for a human to feel pain
Why is this? Why not assume other humans are philosophical zombies[0]? Again, if I can build some dumb machine to say "ouch", lacking all other known physiological correlates to pain (like structures involved in processing pain, withdrawing from 'painful' stimuli, vocalizing sharply when in 'pain'), why isn't it in pain?
>what justification can you have to eat pigs and cause them that pain that you think they feel?
I don't care enough. I eat meat because it's tasty! That doesn't mean I can't try to ensure the things I eat live mildly fulfilling lives before their mostly pain-free deaths. I try to buy meat from places like this [1] because while I want to eat meat and see nothing wrong with it, there's a huge difference between a chicken who has been able to wander about and have a chickeny social network and eat bugs (even if its world is a big open-air warehouse barn) and a chicken who has spent most of its short fat life in a small dark cage. I don't follow this principle all the time, or I'd be restricted from fast food, eating out with friends, etc. I imagine anyone who buys cheap clothes but abhors sweatshops, or who buys consumer electronics but is made uncomfortable by rare-earth mining practices and Foxconn working conditions, or who pays taxes but objects to some horror the government perpetrates with the money, knows what I'm talking about.
[0] https://en.wikipedia.org/wiki/Philosophical_zombie
[1] http://rowefarms.ca/our-farming-philosophies.php