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Book Review - The Significance of Consciousness
The Significance of Consciousness
by Charles P. Siewert
Princeton University Press, 1998
Review by Josh Weisberg
Oct 26th 2001

In The Significance of Consciousness, Charles Siewert argues that "phenomenal consciousness," the subjective feel or character of conscious experience, is the most significant aspect of our mental lives, and, what's more, many consciousness researchers do not adequately account for phenomenal consciousness in their theories. The book is a complex and sometimes difficult work of philosophical investigation, and its style is often hard to penetrate. But Siewert's main points can be succinctly distilled, and they challenge those investigating the mind to thoroughly explain the role of phenomenal consciousness in our lives.

The book opens with a defense of what Siewert calls "the first-person approach to consciousness" (10). Consciousness is known "from the inside" in a distinctly first-person, subjective manner. This knowledge is not infallible or beyond challenge, but, Siewert argues, unless we have good reason to doubt the deliverances of first-person knowledge, we should respect it. Siewert charges that many consciousness researchers ignore this advice in the course of their investigations, and thus deny or seriously downplay the importance of phenomenal consciousness.

Siewert develops and defends this claim by employing a variety of thought experiments that isolate phenomenal consciousness, and arguably show that many theories of consciousness "neglect" (to use Siewert's favored term) the phenomenon. Siewert positively describes phenomenal consciousness as what is "shared by silent speech, other imagery, and sensory experience" (148), but he also picks out the idea in the negative, as that quality lacking in the neurological condition known as "blindsight."

Blindsight is a well-documented neurological deficit that can occur when there is damage to the visual cortex. Subjects claim they can't see anything in the damaged portion of their visual field, but they are substantially better than chance at guessing what is present there. They can identify the form, motion, orientation, and perhaps the color of test stimuli, but they do not make these judgments unless prompted to guess by investigators. The condition suggests that a large amount of visual processing goes on in the absence of consciousness, and many researchers have focused on this result to craft their theories.

Siewert proposes that we imagine a blindsight subject who can use the information gleaned from the blind field without being prompted to guess, by "self cueing." Next we are to imagine a subject with badly degraded but conscious blurry vision who is able to make exactly the same sorts of discriminations as our imaginary self-cueing blindsighter. Both subjects will be able to make the same discriminations and arguably will behave in the same way. But, claims Siewert, one subject, the self-cueing blindsighter, lacks something. That something is phenomenal consciousness.

Siewert then argues that if a theory must deny the coherence or possibility of his thought experiment, the theory neglects phenomenal consciousness. The rejection of the scenario posited by the thought experiment collapses the distinctly phenomenal aspects of consciousness into mere behavioral capacities, capacities that arguably can be exercised without the presence of phenomenal consciousness. This deflates or neglects what Siewert sees as the most important aspect of our conscious lives, that aspect that we know in a distinctly first-personal manner. Siewert claims that theories that identify consciousness with abilities to perform various perceptual discriminations or judgments, as well as theories that identify consciousness with forms of higher-order awareness all must reject the thought experiment, and so neglect phenomenal consciousness.

Having exposed the alleged neglecters of phenomenal consciousness, Siewert goes on to stress the significance of phenomenal consciousness in our lives. He argues that phenomenal consciousness is inherently "intentional," or about the world, because conscious subject can be assessed for accuracy or truth in terms of what their phenomenally conscious states are about. Furthermore, Siewert argues that in addition to mental imagery, nonimagistic thoughts have a phenomenal feel and can differ in their phenomenal character. Siewert ends the book by pointing out that we would sorely miss phenomenal consciousness if we were deprived of it, so much so that we might prefer death to the "zombiehood" that would follow removal of our phenomenal lives.

Siewert's book is thought provoking, but the style of the writing makes it at times difficult to follow. There are paragraphs that require reading and rereading by those well-versed in the consciousness literature, so the work may not prove particularly accessible to the lay reader. Furthermore, the central thought experiment designed to show that many theories neglect phenomenal consciousness is flawed. The additional considerations that are added to the real blindsight case in order to engage specific theories of consciousness become progressively more dubious, and in the end the argument collapses into the claim that we can simply imagine identical beings, one that is phenomenally consciousness and one that is not. This is the shopworn "zombie argument," and it is very controversial whether conceiving of phenomenal zombies demonstrates anything that threatens empirical investigations of consciousness. Though Siewert is undoubtedly correct that, all things being equal, we should respect the deliverances of our first-person access to our minds, and that we should work to adequately explain phenomenal consciousness, he has not established that the theories he attacks have neglected what is significant about consciousness.

© 2001 Josh Weisberg

Josh Weisberg is a doctoral student in the philosophy program at the CUNY Graduate Center