Rocco J. Gennaro2 TerminologyPart of the problem can be that the concept of consciousness is notoriously ambiguous. This
adds to the complexity of the debate and can result in unnecessary confusion. Thus, it is impor-
tant to make several distinctions and to define key terms. The noun ‘consciousness,’ especially in
some abstract sense, is not used very often in the contemporary literature, though it originally
derives from the Latin con (with) and scire (to know). One can have knowledge of the external
world or one’s own mental states through introspection. The primary contemporary interest
lies more in the use of the expressions ‘x is conscious’ or ‘x is conscious of y.’ Under the former
category, perhaps most important is the distinction between state and creature consciousness
(Rosenthal 1993). We sometimes speak of an individual mental state, such as a desire or percep-
tion, as being conscious. On the other hand, we also often talk about organisms or creatures
as conscious, such as when we say that “human beings are conscious” or “dogs are conscious.”
Creature consciousness is simply meant to refer to the fact that an organism is awake, as opposed
to sleeping or in a coma. However, some kind of state of consciousness is normally implied by
creature consciousness; that is, if a creature is conscious, then it must have conscious mental
states. There are of course some possible exceptions, such as one who is sleepwalking. Perhaps
there can also be state consciousness without creature consciousness, such as in the case of
vivid dreams. Due to the lack of a direct object in the expression ‘x is conscious,’ this is usually
referred to as intransitive consciousness, in contrast to transitive consciousness where the phrase
‘x is conscious of y’ is used (Rosenthal 1993). We might say that a person is conscious or aware
of a dog in front of her. Most contemporary theories of consciousness are aimed at explaining
state consciousness, that is, what makes a mental state conscious.
One might think that the term ‘conscious’ is synonymous with, say, ‘awareness,’ or ‘experi-
ence,’ or ‘attention.’ However, it is important to recognize that this is not generally accepted in
some circles. For example, one might hold that there are unconscious experiences depending on
how the term ‘experience’ is defined (Carruthers 2000). More common is the belief that we can
be aware of external objects in some unconscious sense, such as during instances of subliminal
perception. The expression ‘conscious awareness’ does not seem to be redundant. Finally, it is
not clear that consciousness ought to be restricted to attention. It seems plausible to suppose,
for example, that one is conscious of objects to some extent in one’s peripheral visual field, even
though one is attending to a narrower (or focal) set of objects within that visual field. Some of
the disagreement can be purely terminological but some is also more substantial. Needless to say,
contemporary philosophers and psychologists are nearly unanimous in allowing for unconscious
mental states or representations, though they sometimes differ as to whether this applies to all
kinds of mental states including, say, pains and emotions.
Probably the most commonly used notion of “conscious” is captured by Thomas Nagel’s
famous “what it is like” sense (Nagel 1974). When I am in a conscious mental state, there is
“something it is like” for me to be in that state from the subjective or first-person point of view.
When I smell a flower or have a conscious auditory sensation, there is something it “seems” or
“feels like” from my perspective. An organism such as a bat is conscious if it is able to experience
the world through its echolocation senses. There is also something it is like to be a conscious
creature, whereas there is nothing it is like to be a table or tree. This is primarily the sense of
“conscious” used by the authors in this book.
There are still a cluster of other expressions and technical terms associated with Nagel’s sense.
For example, philosophers often refer to conscious states as phenomenal or qualitative states. More
technically, philosophers describe such states as having qualitative properties called “qualia” (sin-
gular, quale). Chalmers explains that a “mental state is conscious if there is something it is like to