What was Wilfred Sellars' idea of functionalism?
Wilfred Sellars (1912-1989) introduced the concept in his 1956 paper, "Empiricism and Philosophy of Mind." According to Sellars, there can be no mental foundations of knowledge such as sense data, and he also rejected the pragmatists' "myth of the given." (By "the given," the pragmatists referred to that part of experience that is not influenced by the perceiver or thinker.) Functionalism, as developed by Sellars, as well as Hilary Putnam (1926-) in his early writings, is the thesis that mental states can be defined by three things: what causes them, their effects on other mental states, and their effects on behavior. That is, mental states can be understood in terms of their functions, which operate like the software of a computer.
What are problems with functionalism as a theory of mind?
Functionalism may result in attributing minds to complex systems that we otherwise would not consider to have minds. It might result in denying the presence of minds that operate according to different causal principles than our own. Indeed, Hilary Putnam (1926-) himself later rejected functionalism on the grounds that beliefs could not be computational states because their content was determined by external facts, and beliefs were also part of a whole system of knowledge. At the same time as Paul Kripke (1940-) and Keith Donnellan (1931-), he developed a new causal or direct theory of meaning, which was published in The Meaning of "Meaning" (1975).
What is the causal theory of meaning?
This theory was first developed by Paul Kripke (1940-), Keith Donnellan (1931-), and Hilary Putnam (1926-) in the 1970s. There used to be a distinction between denotative and connotative, or "intensional" (with an "s," which is different from intention with a "t"), meaning. Denotative meaning was the thing or types of things in the world to which a word referred. Connotative or intentional meaning was the conditions of application of a word or the definition of the word in other words.
According to the causal theory of meaning, also known as "the causal theory of reference," there is a causal history that makes proper names the names of the individuals they are (something like a "baptism.") Natural kind terms, such as water and gold, work in much the same way. To take an example, the term "water" designates the natural H2O; if a substance were called water that was not H2O it would not be water. Putnam famously said of meanings in this regard that they "just ain't in the head." Articles by Kripke, Donnellan, and Putnam on this subject appear in Naming, Necessity and Natural Kinds (1977), edited by Stephen P. Schwartz.
How did Thomas Nagel object to functionalism?
Thomas Nagel (1937-), who is not related to Ernest Nagel (1901-1985), became famous for his 1974 article in The Philosophical Review, "What Is It Like to Be a Bat?" Nagel's point in that article was that the subjectivity of bats eludes us because of the nature of our objective methods of measuring consciousness. He makes the same point in another way with an example of a person tasting chocolate while a brain surgeon observes the part of his brain that is activated. No amount of such observation will allow the observer to taste the chocolate—not even if he licks the part of the brain in question!
Thomas Nagel criticized reductionist views of the human mind with his famous article "What Is It Like to Be a Bat?" (AP).
What is the story about Nagel and the spider?
While Nagel was working in William James Hall at Harvard University one summer, he noticed a spider that lived in the men's urinal. Every time the urinal flushed, the poor arachnid would make a mad dash for its life so as not to drown. Nagel was concerned about what would happen to it when classes were in session and the urinal was flushed with greater frequency.
After long and careful deliberation, Nagel decided to liberate the spider. He carefully removed it from the urinal with a paper towel and placed it in a corner of the room. At first the spider did not move, and Nagel assumed it was getting its bearings. He left town over a holiday weekend, and when he returned the poor spider had still not moved. It was quite dry and quite dead.
Nagel recounts this episode in The View from Nowhere (1986). His implication seems to be that even the greatest compassion and best intentions may miss their objective, due to a lack of understanding of the circumstances of another.
Nagel's main motivations for holding out for the irreducibility of subjective experience are both moral and epistemological. He has shown that the whole of scientific investigation proceeds to increasing points of objectivity toward an ideal "view from nowhere," whereas concrete experience is always someone's view from somewhere. Books by Nagel include: The Possibility of Altruism (1970), Mortal Questions (1979), and The View from Nowhere (1986). Nagel's short introduction to philosophy, What Does It All Mean? (1987), is very accessible.