The absence of a neocortex does not appear to preclude an organism from experiencing affective states. 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. Non-human animals, including all mammals and birds, and many other creatures, including octopuses, also possess these neurological substrates.Their good intentions duly noted, this is not a declaration of a scientific fact.
The truth is that we have no idea what a "conscious state" is. We do not know what neural substrates "generate consciousness". We do not know how to recognize what is "intentional behavior" and what is not. We do not know if consciousness if a property that arises only in biological systems. Nor do we know if consciousness is a binary or graded property. These are all open questions. Any assertion that non-human animals are capable of exhibiting "conscious states" as those experienced by humans is at best a working hypothesis based on vague concepts that need to be clarified.
Note that if we truly had the scientific knowledge and understanding to back up the declaration we should be able to answer the following simple questions. Is a fly's escape behavior to a swat intentional or a mere reflex? What about single-cell organisms that follow up gradients of nutrients? Are they conscious? Is their movement towards the food intentional? The authors must surely have a way to answer these questions to have decided to include the octopus in their list of conscious animals, while leaving the salmon out. But they do not really have an answer. If we had one we could also offer a resolution to one of the biggest problems in philosophy - the problem of other minds. PZ Myers already offered a similar criticism of the declaration and I hope other scientists will jump into this debate as well.
Of course, there are animal activists that had already reached the conclusion that animals are conscious simply by staring into their eyes, they mockingly applaud the new recognition by this group of scientists, and move on to suggest the following:
Some of the conclusions reached in this declaration are the product of scientists who, to this day, still conduct experiments on animals [...] Their own declaration will now be used as evidence that it's time to stop using these animals in captivity and start finding new ways of making a living.Is this so? Can the declaration, assuming it is scientifically valid, be used to argue in such a way? This may be possible if and only if one accepts the following assumptions. First, that the declaration means that consciousness is a binary property - either you have it or not. Thus if animals are conscious they are conscious to the same degree as a normal human (thereby denying the possibility graded levels of consciousness). Second, that consciousness is the only morally relevant property that determines the moral status of a living being. If one accepts these two assumptions the moral status of human and non-human animals ought to be the same. But both assumptions are wrong. Not even the scientists involved in the declaration would agree with the first assumption. People do not think we owe the same moral consideration to the serial killer and to the Dalai Lama, although both are equally conscious. Similarly, we reject the notion that the moral status of a patient in a minimally conscious state is the same as that of a worm. Thus, consciousness alone is insufficient to establish the moral status of living beings.
Opponents of animal research continue to insinuate that the only reason for scientists to experiment on animals is because it supports our livelihood. No, this is not the real reason. The reason for this work is that humans have ability to reduce and eliminate suffering from the world by means of their scientific work. Due to current limitations in technology, in some cases, medical research cannot move forward without access to living organisms at the level of single cells and even molecules. Scientists acknowledge that we owe moral consideration to other living beings, but not to the same degree as human life. We do confront this moral dilemma by carrying out the work while minimizing the number, pain and suffering of animals subjects. Opponents of animal research, on the other hand, readily ask us to stop the work, but fail to provide a moral justification.