Five years ago, on July 7, 2012, a prominent group of scientists signed the Cambridge Declaration on Consciousness. This declaration stated that not only humans, but also a significant amount of animals, including not just vertebrates but also many invertebrates, are conscious beings.
What this means is that they are sentient, that is, they experience what happens to them and have mental states which can be positive or negative for them.
The evidence to support this claim is overwhelming. As the declaration itself stated:
Convergent evidence indicates that non-human animals have the neuroanatomical, neurochemical, and neurophysiological substrates of conscious states along with the capacity to exhibit intentional behaviors. Consequently, the weight of evidence indicates that humans are not unique in possessing the neurological substrates that generate consciousness. Nonhuman animals, including all mammals and birds, and many other creatures, including octopuses, also possess these neurological substrates.”
This is very relevant because the capacity to have positive and negative experiences is what makes a being capable of being harmed. There are powerful reasons to conclude that this is what should matter when it comes to giving someone moral consideration and not discriminating against that being.
To be sure, all the evidence concluding that nonhuman animals are sentient was there already before the Cambridge Declaration on Consciousness was proclaimed in 2012. However, this declaration made it possible to state beyond reasonable objections that there is a (long overdue) scientific consensus about this issue. This is what made this declaration so important.
You can read the whole text of the declaration here:
Five years is a short time, to be sure, but a lot of work in defense of animals and explaining to people that nonhuman animals are fully sentient has been done during this time (for instance, Animal Ethics is actually younger than that, as we started our work just a few years ago). Denials of animal consciousness are now starting to be considered just as other views that try to deny positions about which there is a clear scientific consensus, such as evolution in natural history. We hope more progress on this topic will be done in the years to come and that animal consciousness will be considered a more serious issue.
Allen, C. & Bekoff, M. (1997) Species of mind, Cambridge: MIT Press.
Allen, C. (2004) “Animal pain”, Noûs, 38, pp. 617-643.
Baars, B. J. (2001) “There are no known differences in brain mechanisms of consciousness between humans and other mammals”, Animal Welfare, 10, pp. 31-40.
Braithwaite, V. A. (2010) Do fish feel pain?, Oxford: Oxford University Press.
DeGrazia, D. (1996) Taking animals seriously: Mental life & moral status, Cambridge: Cambridge University Press, ch. 5.
Edelman D. & Seth, A. (2009) “Animal consciousness: A synthetic approach”, Trends in Neuroscience, 9, pp. 476-484.
Elwood, R. W. & Appel, M. (2009) “Pain experience in hermit crabs?”, Animal Behaviour, 77, pp. 1243-1246.
Fiorito, G. (1986) “Is there ‘pain’ in invertebrates?”, Behavioural Processes, 12, pp. 383-388.
Gentle, M. J. (1992) “Pain in birds”, Animal Welfare, 1, pp. 235-247.
Gherardi, F. (2009) “Behavioural indicators of pain in crustacean decapods”, Annali dell´Istituto Superiore di Sanita, 45, pp. 432-438.
Glock, H. (2000) “Animals, thoughts and concepts”, Synthese, 123, pp. 35-64.
Griffin, D. R. (1981) The question of animal awareness, Los Altos: William Kaufman.
Griffin, D. R. (2001) Animal minds: Beyond cognition to consciousness, Chicago: Chicago University Press.
Huffard, C. L. (2013) “Cephalopod neurobiology: An introduction for biologists working in other model systems”, Invertebrate Neuroscience, 13, pp. 11-18.
Kamenos, N. A.; Calosi, P. & Moore, P. P. (2006) “Substratum-mediated heart rate responses of an invertebrate to predation threat”, Animal Behaviour, 71, pp. 809-813.
Kirkwood, J. K. & Hubrecht, R. (2001) “Animal consciousness, cognition and welfare”, Animal Welfare, 10, pp. 5-17.
Knutsson, S. (2015a) The moral importance of small animals, Master’s thesis in practical philosophy, Gothenburg: University of Gothenburg [accessed on 4 January 2016].
Lurz, R. W. (ed.) (2009) Philosophy of animal minds: New essays on animal thought and consciousness, Cambridge: Cambridge University Press.
Mather, J. A. (2001) “Animal suffering: An invertebrate perspective”, Journal of Applied Animal Welfare Science, 4, pp. 151-156.
Mather, J. A. (2008) “Cephalopod consciousness: Behavioral evidence”, Consciousness and Cognition, 17, pp. 37-48.
Nagel, T. (1974) “What is it like to be a bat?”, Philosophical Review, 83, pp. 435-450.
Panksepp, J. (2004) Affective neuroscience: The foundations of human and animal emotions, New York: Oxford University Press.
Radner, D. & Radner, M. (1986) Animal consciousness, New York: Prometheus.
Robinson, W. S. (1997) “Some nonhuman animals can have pains in a morally relevant sense”, Biology and Philosophy, 12, pp. 51-71.
Rollin, B. E. (1989) The unheeded cry: Animal consciousness, animal pain and science, Oxford: Oxford University Press.
Sherwin, C. M. (2001) “Can invertebrates suffer? Or, how robust is argument-by-analogy?”, Animal Welfare, 10, pp. 103-118.
Tye, M. (2017) Tense bees and shell-shocked crabs: Are animals conscious?, New York: Oxford University Press.