Copyright © 1999 Massachusetts Institute of Technology
A prolific and gifted writer, whose broad learning extended from neurophysiology and EVOLUTION to the literature of six languages, Sigmund Freud (1856-1939) was one of the most influential scientists of the late nineteenth and early twentieth centuries. He was also one of the most controversial scientists of any time, so much so that both his critics and admirers have occasionally succumbed to the temptation to deny that he was a scientist at all.
Freud's positive and negative reputations flow from the same source -- the extraordinary scope of his theories. Although the notions of unconscious ideas and processes did not originate with Freud, having philosophical antecedents in Gottfried Leibniz's (1646-1716) theory of petites perceptions and psychiatric antecedents in the work of, inter alia, Pierre Janet (1859 - 1947), Freud made them the centerpiece of his complex theory of the mind. Unlike other psychiatrists, Freud took unconscious ideas and processes to be critical in explaining the behavior of all people in all circumstances and not merely the outré actions of psychotics. Unlike Leibniz and his followers, Freud presented unconscious ideas not merely as a theoretical necessity, but as the key to human action. Through his spirited defense of the necessity and importance of unconscious ideas and processes, he gave these concepts theoretical respectability, almost in spite of their associations with him.
The explanatory scope of unconscious ideas and processes was enormous for Freud, because he saw psychoanalysis (see PSYCHOANALYSIS, CONTEMPORARY VIEWS OF and PSYCHOANALYSIS, HISTORY OF) as bridging the gap between the biological and the "human" sciences. Freud's early training in neurophysiology led him to try to ground psychological theorizing in the known structures of the brain. His incomplete manuscript, "Project for a Scientific Psychology" attempted to relate specific psychological functions, such as learning and memory, to recently discovered properties of the neurons. In this respect, his methodological principles exactly paralleled the current view in cognitive science that psychological theorizing must be consistent with and informed by the most recent knowledge in neuroscience. Freud was also an avid supporter of DARWIN and was explicit in stating that his theory of sexual and self-preservative instincts was firmly rooted in (evolutionary) biology. Prototypical of his synthetic approach to knowledge, he made a bold conjecture about an important relation between the findings of neurophysiology and evolutionary biology. If, as nearly all psychologists agreed, the mind functioned as a reflex, then it required constant stimulation, and if, as Darwin argued, the sexual instinct is one of the two most important forces governing animal life, then these findings could be brought together under a more comprehensive theory that sexual instincts (libido) drove the nervous system. Although Freud, his disciples, and his critics often present libido theory as an extrapolation from the sexual difficulties of his patients, its real strength and appeal came from its plausible biological premises.
Thanks to Darwin's influence, sexuality also played an important role in the social sciences of the late nineteenth century. A methodological imperative of evolutionary anthropology and sociology was to connect sophisticated human achievements to "primitive" conditions shared with animals, and sexual behavior was the most obvious point of connection. Given these trends in social science, Freud was able to make "upward" connections between psychoanalysis and the social sciences, as well as "downward" connections to neurophysiology and biology. In his efforts to find links among all the "mental" sciences, Freud's methodological approach again bears a striking resemblance to the interdisciplinary emphasis of current cognitive science. This approach was also the basis of the tremendous appeal of psychoanalysis: he believed that he had a theory that could provide biologically grounded explanations, in terms of sexual and self-preservative instincts and the various mental processes that operated on them, for everything from psychotic symptoms, dreams, and jokes to cultural practices such as art and religion.
Freud's theories of CONSCIOUSNESS and the EMOTIONS were also the product of an interdisciplinary synthesis between psychiatry and philosophy. Individuals whose behavior was driven by natural, but unconscious, emotional forces needed treatment in order to gain control of their lives by bringing the forces that govern them to consciousness. This was possible, Freud believed, because affective states were also cognitive and so could be made conscious through their ideational components. Although the Project offered some speculations about the qualitative character of consciousness, Freud's later approach was functionalist. Conscious ideas differed from the unconscious, because they could be expressed verbally, because they were subject to rational constraints such as consistency, and because they could interact with sensory evidence.
Although Freud regarded the consilience of psychoanalysis with the biological and social sciences as the strongest argument in its favor, important changes in both the biological and social sciences undermined the plausibility of his basic assumptions about how mental processes worked. Rather than alter the scientific foundations of psychoanalysis, he continued to try to increase its scope and influence, leading to charges of disingenuousness and even pseudoscience. Despite Freud's tarnished reputation, many of his central substantive and methodological assumptions about studying the mind have reemerged with the rise of cognitive science, in particular, the assumption (from his teacher BRENTANO) that mental states are intentional (see INTENTIONALITY) and must be understood in terms of their contents, but that they are likewise physical and must be related to neuroscience, the assumption (which he described as an extension of KANT) that most mental processes are unconscious, the view that cognition and emotion are not separate faculties, but deeply intertwined aspects of mentality, and the basic methodological assumption that the biological and "human" sciences must learn from each other, because the ultimate goal is to develop a comprehensive theory of the social, psychological, and physical aspects of mentality. Further, although its emphasis on input-output computation has given cognitive science a synchronic time scale for much of its history, recent work on ARTIFICIAL LIFE and EVOLUTIONARY COMPUTATION reintroduces the sort of diachronic or genetic approach that Freud thought was essential in understanding the complexities of a mentality that was produced via individual development and the evolution of the species.
Ellenberger, H. (1970). The Discovery of Consciousness. New York: Basic Books.
Erdelyi, M. H. (1985). Psychoanalysis: Freud's Cognitive Psychology. New York: W. H. Freeman.
Freud, S. (1966). Project for a Scientific Psychology. Preliminary Communication (to Studies in Hysteria, with (Josef Brauer)). Three Essays on Sexuality. The Unconscious. Instincts and their Vicissitudes. The Ego and the Id. All can be found in The Complete Psychological Works of Sigmund Freud. James Strachey., Ed. 24, vol. London: The Hogarth Press.
Kitcher, P. (1992). Freud's Dream: A Complete Interdisciplinary Science of Mind. Cambridge, MA: Bradford/MIT Press.
Sulloway, F. (1994). Freud: Biologist of the Mind. New York: Basic Books.
Copyright © 1999 Massachusetts Institute of Technology