Philosophical background to the cognitive revolution

Philosophical background to the cognitive revolution John Goldsmith Linguistics as a cognitive and computational science Class 2 January 2000

Modern philosophy... • By general agreement or convention begins with René Descartes (1596-1650)

Descartes grappled with the problem of modernism raised by the rise of capitalism and Protestantism: when tradition is no longer secure, what is the basis of our certainty -- of anything?

As you may have noticed, no one has provided the definitive answer to Descartes' question. His answer was: • first of all, introspection provides certainty; • second of all, God provides certainty. • Way down his list was the sense and perception.

Epistemology: the study of the justification of knowledge? There are a number of differences that we can identify between empiricism and rationalism, but we will be interested primarily in the differences of their views of epistemology: the origins and foundations and justifications of knowledge.

Empiricists/Rationalists: Fundamental issue: “Everything that is in the mind comes from the senses”: Yes or No? Empiricism: Yes Rationalism: No: Everything that is in the mind comes from the senses: except the mind itself. See also http://cogweb.english.ucsb.edu/CogSci/Empiricism.html

Harry Bracken, in a paper heavily influenced by Chomsky’s view of Descartes and of language: http://www.mullasadra.org/papers/harry_m_bracken.html

Rationalism Leading contributors: • Spinoza • Descartes • Leibniz (Leibnitz) Knowledge has a base of which we can be certain. Mathematics illustrates this. We know general statements (universals) which logically could not be the result of (a finite number of) sense impressions

Empiricism Leading contributors: • John Locke (1632-1704) • David Hume(1711-1776) And the influence of Isaac Newton is not to be ignored!

Rationalism Its view of the fundamental problem to work on: carefully deducing from clear premises what we can be certain of. Problem posed by critics: those premises reflect non-necessary properties of the real world. How can that be? Too much of a coincidence not to be the result of learning! Empiricism Fundamental problem: the justification of any sort of generalization, going beyond the data. (“…Yes, on this side…”) Problem posed by its critics: But we do know things with certainty, which empiricism can’t account for.

Probabilistic reasoning Development of understanding of statistics Logical inference, in which all consequences are as certain as least certain of postulates/axioms. Paradigm of knowledge

Rationalists: Innate ideas Empiricists: No innate ideas, of course.

The British empiricists... notably John Locke (1632-1704) and David Hume (1711-1776), were not satisfied with Descartes’ answers. Their introspection provides them with no certainty, they said, and all that they found in their minds was sensory impressions, anyway.

John Locke The Locke page: http://landow.stg.brown.edu/victorian/religion/locke1.html Also: http://cogweb.english.ucsb.edu/CogSci/Locke.html

David Hume Hume's Enquiry concerning human understanding (section 2) 1748...

But though our thought seems to possess this unbounded liberty, we shall find, upon a nearer examination, that it is really confined within very narrow limits, and that all this creative power of the mind amounts to no more than the faculty of compounding, transposing, augmenting, or diminishing the materials afforded us by the senses and experience. When we think of a golden mountain, we only join two consistent ideas, gold, and mountain, with which we were formerly acquainted.

A virtuous horse we can conceive; because, from our own feeling, we can conceive virtue; and this we may unite to the figure and shape of a horse, which is an animal familiar to us. In short, all the materials of thinking are derived either from our outward or inward sentiment: The mixture and composition of these belongs alone to the mind and will. Or, to express myself in philosophical language, all our ideas or more feeble perceptions are copies of our impressions or more lively ones.

To prove this, the two following arguments will, I hope, be sufficient. First, when we analyze our thoughts or ideas, however compounded or sublime, we always find that they resolve themselves into such simple ideas as were copied from a precedent feeling or sentiment. Even those ideas, which, at first view, seem the most wide of this origin, are found, upon a nearer scrutiny, to be derived from it.

The idea of God, as meaning an infinitely intelligent, wise, and good Being, arises from reflecting on the operations of our own mind, and augmenting, without limit, those qualities of goodness and wisdom. We may prosecute this enquiry to what length we please; where we shall always find, that every idea which we examine is copied from a similar impression. Those who would assert that this position is not universally true nor without exception, have only one, and that an easy method of refuting it;

by producing that idea, which, in their opinion, is not derived from this source. It will then be incumbent on us, if we would maintain our doctrine, to produce the impression, or lively perception, which corresponds to it. Secondly. If it happen, from a defect of the organ, that a man is not susceptible of any species of sensation, we always find that he is as little susceptible of the correspondent ideas. A blind man can form no notion of colours; a deaf man of sounds.

Rationalism • Associated with René Descartes, Gottfried W. Leibniz (1646 - 1716), and Spinoza.

Leibniz at home. Check outthese web sites, too. http://www-groups.mcs.st-and.ac.uk/ ~history/Mathematicians/Leibniz.html http://www.maths.tcd.ie/pub/ HistMath/People/Leibniz/RouseBall/ RB_Leibnitz.html http://mally.stanford.edu/leibniz.html

Structure of hierarchies There is a close connection -- not a parallel, but a connection -- between epistemological differences of R/E and their views of the structure of hierarchies. I use the term in a way slightly more specific than everyday speech. In everyday speech, the following are hierarchies:

Roman Jakobson Family trees Thomas Sebeok Morris Halle John McCarthy Mark Liberman

Or authority structures: President Provost Dean of College Dean of Humanities Chair of Lx Chair...

This is the kind of hierarchy I mean, though: US Illinois Minnesota Springfield Evanston Chicago Hyde Park

Another example: animals tissues cells molecules atoms

Hierarchy The crucial property is that an object on level I is composed of a large number of (similar) objects on level I+1, and each level has properties that are not (obviously) comparable to properties on another level, especially on a neighboring level.

All swans are white My pet swan is white My sister’s swan is white

How do hierarchies arise?How are they governed?

Structure of Hierarchies

Immanuel Kant 1724-1804

Kant's message was that the possibility of human knowledge involves the active participation of the mind -- knowledge presupposes, we might say today, the active participation of a knower. In an important sense, he backs Descartes, but the mind is not one more sense among others: it is the underlying system.

Synthetic apriori truths ...were what Kant thought would be characteristic of what we know that derives not from experience but from our status as active cognizers. But he never considered the possibility that we could study our neighbors. He looked, instead, for the pure forms of sensible intuition that were presupposed in our perceptions and our thought.

G W F Hegel 1770-1831,Karl Marx 1818-1883 Through Fichte, Hegel, and Marx arose a tradition that focused on human action and human history being the foundation on which certainty (such as can be found) must rest.

John Dewey 1859-1952 • Discussion by Richard Field on the internet:

In Dewey's view, traditional epistemologies, whether rationalist or empiricist, had drawn too stark a distinction between thought, the domain of knowledge, and the world of fact to which thought purportedly referred: thought was believed to exist apart from the world, epistemically as the object of immediate awareness, ontologically as the unique aspect of the self. The commitment of modern rationalism, stemming from Descartes, to a doctrine of innate ideas, ideas constituted from birth in the very nature of the mind itself, had effected this dichotomy; but the modern empiricists, beginning with Locke, had done the same just as markedly by their commitment to an introspective methodology and a representational theory of ideas. The resulting view makes a mystery of the relevance of thought to the world: if thought constitutes a domain that stands apart from the world, how can its accuracy as an account of the world ever be established? For Dewey a new model, rejecting traditional presumptions, was wanting, a model that Dewey endeavored to develop and refine throughout his years of writing and reflection.

... In his early writings on these issues, such as "Is Logic a Dualistic Science?" (1890) and "The Present Position of Logical Theory" (1891), Dewey offered a solution to epistemological issues mainly along the lines of his early acceptance of Hegelian idealism: the world of fact does not stand apart from thought, but is itself defined within thought as its objective manifestation. But during the succeeding decade Dewey gradually came to reject this solution as confused and inadequate.

A number of influences have bearing on Dewey's change of view. For one, Hegelian idealism was not conducive to accommodating the methodologies and results of experimental science which he accepted and admired. Dewey himself had attempted to effect such an accommodation between experimental psychology and idealism in his early Psychology (1887), but the publication of William James' Principles of Psychology (1891), written from a more thoroughgoing naturalistic stance, suggested the superfluity of idealist principles in the treatment of the subject.

Second, Darwin's theory of natural selection suggested in a more particular way the form which a naturalistic approach to the theory of knowledge should take. Darwin's theory had renounced supernatural explanations of the origins of species by accounting for the morphology of living organisms as a product of a natural, temporal process of the adaptation of lineages of organisms to their environments, environments which, Darwin understood, were significantly determined by the organisms that occupied them. The key to the naturalistic account of species was a consideration of the complex interrelationships between organisms and environments. In a similar way, Dewey came to believe that a productive, naturalistic approach to the theory of knowledge must begin with a consideration of the development of knowledge as an adaptive human response to environing conditions aimed at an active restructuring of these conditions. Unlike traditional approaches in the theory of knowledge, which saw thought as a subjective primitive out of which knowledge was composed, Dewey's approach understood thought genetically, as the product of the interaction between organism and environment, and knowledge as having practical instrumentality in the guidance and control of that interaction. Thus Dewey adopted the term "instrumentalism" as a descriptive appellation for his new approach.

Dewey's first significant application of this new naturalistic understanding was offered in his seminal article "The Reflex Arc Concept in Psychology" (1896). In this article, Dewey argued that the dominant conception of the reflex arc in the psychology of his day, which was thought to begin with the passive stimulation of the organism, causing a conscious act of awareness eventuating in a response, was a carry-over of the old, and errant, mind-body dualism. Dewey argued for an alternative view: the organism interacts with the world through self-guided activity that coordinates and integrates sensory and motor responses. The implication for the theory of knowledge was clear: the world is not passively perceived and thereby known; active manipulation of the environment is involved integrally in the process of learning from the start.

A detailed genetic analysis of the process of inquiry was Dewey's signal contribution to Studies. Dewey distinguished three phases of the process. It begins with the problematic situation, a situation where instinctive or habitual responses of the human organism to the environment are inadequate for the continuation of ongoing activity in pursuit of the fulfillment of needs and desires. Dewey stressed in Studies and subsequent writings that the uncertainty of the problematic situation is not inherently cognitive, but practical and existential. Cognitive elements enter into the process as a response to precognitive maladjustment.

The second phase of the process involves the isolation of the data or subject matter which defines the parameters within which the reconstruction of the initiating situation must be addressed. In the third, reflective phase of the process, the cognitive elements of inquiry (ideas, suppositions, theories, etc.) are entertained as hypothetical solutions to the originating impediment of the problematic situation, the implications of which are pursued in the abstract. The final test of the adequacy of these solutions comes with their employment in action. If a reconstruction of the antecedent situation conducive to fluid activity is achieved, then the solution no longer retains the character of the hypothetical that marks cognitive thought; rather, it becomes a part of the existential circumstances of human life.

The error of modern epistemologists, as Dewey saw it, was that they isolated the reflective stages of this process, and hypostatized the elements of those stages (sensations, ideas, etc.) into pre-existing constituents of a subjective mind in their search for an incorrigible foundation of knowledge. For Dewey, the hypostatization was as groundless as the search for incorrigibility was barren. Rejecting foundationalism, Dewey accepted the fallibilism that was characteristic of the school of pragmatism: the view that any proposition accepted as an item of knowledge has this status only provisionally, contingent upon its adequacy in providing a coherent understanding of the world as the basis for human action.

One traditional question that Dewey addressed in a series of essays between 1906 and 1909 was that of the meaning of truth. Dewey at that time considered the pragmatic theory of truth as central to the pragmatic school of thought, and vigorously defended its viability. Both Dewey and William James, in his book Pragmatism (1907), argued that the traditional correspondence theory of truth, according to which the true idea is one that agrees or corresponds to reality, only begs the question of what the "agreement" or correspondence" of idea with reality is. Dewey and James maintained that an idea agrees with reality, and is therefore true, if and only if it is successfully employed in human action in pursuit of human goals and interests, that is, if it leads to the resolution of a problematic situation in Dewey's terms. The pragmatic theory of truth met with strong opposition among its critics, perhaps most notably from the British logician and philosopher Bertrand Russell.

Ernst Mach • 1838-1916 (Prague, Vienna) A scientist who explored many areas....

Mach • A thorough-going empiricist, but not of the drawing-room sort (like Hume) -- rather, of the scientific, go-out-and-study sort (like James and Dewey). The stuff of human knowledge and experience is sensory; the purpose of intelligence (and science, therefore) is to summarize experience economically.

On Mach's view, it was critical to be constantly on the alert for letting scientific constructs become taken for something that they are not, i.e., as real as sensory impressions. Everything non-sensory was open to critical reexamination. This was important in the liberating atmosphere that led to Poincaré and Einstein's reconsideration of space and time (special relativity, general relativity).

Mach -> Vienna circle • The Verein Ernst Mach was established by Otto Neurath; it evolved into the Vienna Circle, in which logical positivism was born. One of its leading light was Rudolph Carnap, who came to the University of Chicago in 1936 (-1952; d. 1970), and whose work helped Bertrand Russell discover Walter Pitts.

Allen Janik and Stephen Toulmin • MACHs Reduktion jeder Erkenntnis auf eine letzte Basis von Empfindungen ist die Grundlage seines ganzen Denkens. Es ist Aufgabe aller wissenschaftlichen Bemühungen, die grundlegenden Sinnesdaten auf einfachste und ökonomischste Weise zu beschreiben und zu systematisieren. .... Das Merkmal der Einfachheit und Denkökonomie ist das spezifisch wissenschaftliche Charakteristikum einer Darstellung von Erfahrung. MACHs Perspektive ist also die des Phänomenalisten... (Wittegenstein's Vienna, this German translation is on the Web!)

Philosophical background to the cognitive revolution