How can we know?
Unfortunately, we can't. Truth be told, I can't even know that you are conscious. That said, I do think that the benefit of the doubt should be given far more then it usually is. The mind is amazing, but the method in which it is made up isn't necessarily all that rare in the world. I would argue that not only does your dog have a mind, but plants likely have a mind as well. Though to a much lesser extent. I'm actually writing a series on the mind, and my latest article goes into why I believe that plants likely have a mind if you are interested.
Good point! I was actually thinking about the plants having a mind the other day when walking in the hills. It is said that if you talk kindly to them they bloom, but if you talk to them badly they die.
I agree with you, we can't be sure of anyone's consciousness yet everything has a purpose.
Will check your articles ;)