Consciousness is a word like soul. Most people believe they know what the word means, but are actually hard-pressed to provide a definition. Even if a definition is given, it is likely that it will not agree with the one provided by their neighbor. The importance of clarity and precision in the definition of consciousness is greater than for a word like soul, since consciousness is often used in scientific literature. A scientific term must have a universally agreed upon definition, or it is outside the arena of scientific investigation. A researcher cannot prove or disprove an aspect of consciousness if its definition is vague or transitional.
One problem in defining consciousness is the placement of boundaries within the total stream of thought. There is an ongoing debate whether animals are conscious, and much of the debate hinges on the limitations of conscious thought. It should not be overlooked that all definitions have an arbitrary feature, and consensus is the most important feature of any definition. A proposed functional definition of consciousness is spoken or internal language that may potentiate goal directed behavior. This definition is purposely limited to language, as this is the one cognitive skill believed to be unique among humans.
The more humans observe and understand mammalian behavior, the more their abilities are reminiscent of human behavior. The visual memory of squirrels exceeds that of humans, and complex social behavior is not limited to primates. Both primates and porpoises use symbols effectively, and the number of animals on this list will likely grow in the future. The dictionary definition of consciousness could even include insects, as it is defined as an awareness of an external or internal object. Perhaps soldier ants are not aware of internal representations, but they must be aware of external objects to defend the colony. Primates are able to use feeling words in a reliable and appropriate fashion, such that they are aware of internal representations. The typical definition of consciousness is hardly limited to humans.
To limit the definition of consciousness to language deliberately differentiates it from cognition displayed in the animal kingdom. Internal dialogue composed of auditory symbols is unique to humans, as no other creature has been observed using speech. Dolphins and humpback whales may be an exception, but at least the exceptions would be few, and the term would still retain its scientific usefulness. Humans have feeling states that accompany a sense of belief or disbelief, but these feelings are currently impossible to prove in other humans-let alone animals. In no way is the definition of consciousness expounded intended to limit thought to verbal expression. In no way, as Wittgenstein postulated, does language put limits on thought or what it is possible to know. Language is an emergent phenomenon of the human brain that allows us to hypothesize solutions and categorize knowledge in a way that is impossible for creatures without this skill.
The second part of the proposed definition of consciousness entails its importance in accomplishing goals. Humans that are brain injured and confused may exhibit speech, but it often a jumble of words and sentences that are senseless. The proposition that a person’s speech lacks sense is that it doesn’t have a goal. Even angry rambling speech communicates the current feeling state and intentions (goals) of the speaker. People who lack goal-directed speech could be considered as not conscious, even though some form of internal speech may still transpire. People with rambling disconnected speech rarely retain memories of events, because their brain is not encoding information in a way that can be stored and retrieved. Please note that “not conscious” was used in lieu of “unconscious.” Most of the information that flows into our senses is unconscious; including an awareness of our bodily states. Consciousness would have little adaptive value if humans were constantly assaulted by a torrent of sensations and memories.
The use of the word “may” in the definition of consciousness is an acknowledgement that not all spoken or internal speech is goal directed. The word “may” could be replaced with “has the potential to.” Humans may ruminate on works of art that do not result in an observable behavior. Psychologists often differentiate speech that is rambling as “illogical” or is not “pertinent” to the situation. Both these terms have precise definitions, but are less than useful if the person cannot or will not speak. Most people with rambling speech do not exhibit effective goal directed behavior, yet there is at least one exception. Some strokes result in speech that is jumbled or absent, yet the patient appears to function in a goal directed fashion. Psychologists and speech pathologists have conjectured that a patient’s “internal speech” or “deep language structure” is relatively preserved. This would fit in neatly with the current definition of consciousness. Unfortunately, deep language structure is a phenomenon that is not readily observable. As such, it is unlikely to be proved or disproved by the scientific method. A psychologist may observe a rambling or mute patient acting in a goal directed fashion, but they cannot be sure if the patient is actually conscious by this measure alone.
The proposed definition of consciousness is intended to differentiate human from animal cognition. It is a more language dependent conceptualization than what is offered in textbooks. An awareness of an internal or external object is not only difficult to observe, but it tends to support the blurry boundary between animal and human cognition. It is hoped that the definition of consciousness offered here will enhance the concept’s explanatory power and scientific usefulness. Many scientists and clinicians may be uncomfortable with the pairing of language and consciousness, but speech is the only observable that provides evidence of self-awareness. Goals may be inferred with some accuracy from observed behavior, which is why they are crucial to the definition. Taken together, the current definition has the potential to accurately classify a human or animal as conscious-or not.