We can never be sure anyone else is sentient. But we can be sure enough in the case of other people, nonhuman primates, mammals, birds, fish, lower vertebrates and invertebrates as to make scepticism academic and otiose (not to mention monumentally cruel). The only genuinely uncertain kinds of cases are jellyfish, microbes and plants. The rest is not about whether but what they are feeling.

Author Biography

Stevan Harnad is Professor of cognitive science at Université du Québec à Montréal and University of Southampton. His research is on category learning, language evolution, consciousness, and open access. Founder and former editor of the journal Behavioral and Brain Sciences, Harnad is becoming increasingly active in the problems of animal welfare, animal rights and animal law. http://bit.ly/StevanHarnadUQÀM