In April, over 280 researchers (a number that has since grown to 480) released a statement on animal consciousness asserting that "there is solid scientific support for attributing conscious experience to other mammals and birds" and "at least one realistic possibility of conscious experience in all vertebrates... and many invertebrates." However, this broad claim may hinder scientific research in several ways.
The accompanying reference document supporting the statement, called the New York Declaration on Animal Consciousness, focuses on phenomenal consciousness, a term introduced by philosopher Ned Block to describe the 'pure' qualitative aspects of subjective experiences, such as the redness of red or the painfulness of pain. Block used the term to distinguish phenomenal consciousness from other notions of consciousness, such as the ability to behave flexibly, which includes learning and meaningful responses to stimuli.
By definition, these phenomenal experiences do not necessarily lead to significant cognitive consequences: they can be fleeting, and an animal may not notice them. Therefore, they can be difficult to measure experimentally. In fact, the empirical investigation of phenomenal consciousness is controversial even among humans. For instance, a person may not follow a series of letters on a license plate closely enough to recall them all immediately, but they may accurately report certain numbers when given an appropriate cue to focus on only a subset. Some researchers interpret this observation as evidence that the viewer processes all the letters and is incredibly aware of them. Such arguments remain contested, but they illustrate the meticulous work needed to establish the existence of phenomenal consciousness or its absence.
Because there is no agreed-upon neural signature for phenomenal consciousness, the declaration relies instead on evidence that generally concerns flexible behavior, arguing that manifestations of learning, memory, problem-solving, and self-awareness in animals are signs of phenomenal consciousness—a clear deviation from the definition. In personal correspondence, Jonathan Bouleau, one of the authors of the declaration, asserts that while phenomenal consciousness is conceptually distinct from forms that support flexible behaviors, the two may empirically prove identical or at least closely related.
However, it is already known that they can dissociate. For instance, individuals with blindsight report having no subjective experience in their affected visual field. Yet they can guess the identity of visual stimuli, spontaneously avoid obstacles, and learn to respond to threats presented in their 'blind' fields. Similarly, decapitated insects and even plants show signs of learning. In other words, none of the evidence cited in support of the declaration unequivocally indicates phenomenal consciousness rather than the general ability to behave flexibly. The latter can evidently exist without the former.
This does not mean that birds and other mammals definitely lack subjective experiences. Like many others, I would like to believe that these animals are likely incredibly conscious. Some findings may be suggestive, but they are far from definitive. Making a public statement that there is 'solid evidence' of phenomenal consciousness in animals suggests that we can already measure it reliably and unequivocally, which is not yet the case. Prematurely declaring a consensus risks hindering efforts to develop more precise means of assessment.
Such broad statements can also have other negative consequences. The media message is that experts have declared insects conscious, which could galvanize misinformed activism for animal rights. Statements about fish sensitivity, for example, have stifled research, making it more difficult to obtain funding.
Even though it is the media's responsibility to avoid exaggeration, it is not surprising that this has occurred in this case. Some terms in the statement, promoted during a public event, are ambiguous. Given that there are well-known skeptics (e.g., Joseph LeDoux) of animal consciousness, even in rodents, it is not clear what 'broad agreement' the statement refers to. Regarding phenomenal consciousness in birds, it is not at all clear that there is actually 'solid scientific support.'
Indeed, the science of consciousness has become a highly prized area that attracts significant media attention. Last year, a study invited several reports in major scientific and popular media before peer review, and this widespread attention ultimately drew significant criticism from within the scientific community.
This new declaration is generating the same type of attention, through media activities rather than rigorous peer review. I fear that these recent events have served to 'normalize' the way the New York Declaration is presented. Years ago, when a similar Cambridge Declaration on Consciousness was made, dozens of authors signed an open letter criticizing its premature nature. Today, it seems that the zeitgeist has somewhat shifted.
Increasingly, the science of consciousness is being called upon to make far-reaching ethical statements on controversial topics such as abortion, organoid research, and the sensitivity of artificial intelligence. However, the current state of research requires a level of caution and humility from which we, as a community, are unfortunately straying. A likely outcome—and another way in which the declaration could harm research—is that more serious individuals will cease to take the discipline seriously. More worryingly, this could tarnish the reputation of science as a whole.