Well, since I guess I need to start somewhere, I shall start with a favorite article of mine. Written by an evolutionary psychologist named Humphrey, he deviates from typical evolutionary psychology, in which processes such as empathy and mind reading are important and evolved mechanisms would be investigated, by instead tackling the question why such processes are necessary for the individual in the first place. To him, these processes are necessary because of consciousness is private.
Humphrey theorizes that bodily actions occur because of the individual acting. This is to say that the cause of movement is the individual self, not another individual. However, the internal component, the drive to act, is private and unknown to the observer. Secondly, he theorizes that sensation is a bodily action. When an individual senses, sensations are not the outside world acting upon the individual, but is the individual observing physiological changes. Seeing the color red is realizing the the eye is in a state of what is known to the individual as observing red. Consciousness is the realization that one is engaged in such an act. However, this realization is both internal and private like the drive for action. As such, it is only known to the individual.
And since consciousness is private, it helps to create a barrier between individuals. From this comes the phrase society of selves. We are each a single self, and I, and society is comprised of a collection of selves, a group of Is. However, individuals within a society do attempt to commune by utilizing empathy, theory of mind, or other sociocognitive processes. These function by allowing the individual to utilize one’s own consciousness to determine the consciousness of another. As a result, the other is never truly known, but the individual can only understand his or her interpretation of the other individual. In this sense, we will always be alone.
To me, this makes intuitive sense. Our conceptions of anything that occurs outside of the self is understand only through interpretation by the self. Language serves an important means through which this process occurs. Language is symbolic, existing outside of the individual in the shared practices of the the society. Language serves the function of acting as a shared reference to common internal representations. The word red symbolizes our conscious experience of red. Well the experience of red is common to all individuals, each individual has a unique conceptualization of red, so that when I make reference to the concept of red through its symbolic word, another can generally understand what is being referenced, but only I can understand exactly the form of what I am referencing.
Given this view, complex speech acts such as metaphors seem to function because of common ground. the word that references this concept is generally excepted by all members of a society to make reference to that internal concept. Additionally, the internal concept referenced in a metaphor is complex and nuanced in form. However, its form is expected to have enough common ground based on shared experience that the other individual would be able to interpret the concept in the way in which the speaker intended given their own conscious experiences.
Typically, this process functions smoothly. However, in some groups of individuals with psychopathology, this process may not necessarily occur in this expected manner. For example, take schizophrenics with delusions. These individuals have been suggested to have deficits in theory of mind while delusional, however during non-delusional periods these deficits disappear (Frith & Corcoran, 1996). Have these individuals lost the ability to produce socially meaningful speech due to theory of mind impairments so that delusions are merely failed metaphors? A second example is that of the individual with severe autism. Unlike schizophrenics, these individuals have chronic deficits in theory of mind that impair their ability to develop complex speech (Diesendruck 2007). Are these individuals unable top understand metaphor because to them the word that acts as a reference is not symbolic but a concrete learned association?
Frith, C.D., & Corcoran, R. (1996). Exploring Theory of Mind in People With Schizophrenia.Psychological Medicine 26: 521-30.
Diesendruck, G. (2007). Word learning without Theory of Mind: Possible but Useless. Coevolution of Language and ToM. Retrieved October 10, 2007, from http://www.interdisciplines.org/coevolution/papers/9
Humphrey, N. (2007.) The society of selves. Philosophical transactions of the royal society b: biological sciences, 362 (1480). pp. 745-754.