In a recent article (“Introspective Physicalism as an approach to the science of consciousness”, Cognition 2001 – special issue on Consciousness ed. Stanislas Dehaene), I argue that psychology is ready and able to accommodate a paradigm shift by incorporating introspective evidence into scientific accounts of cognitive processes. My claim is that, provided the right theoretical approach and methodology is adopted, it is possible to avoid the difficulties that have been historically associated with introspection. In the article, I outline an approach and I discuss some methodological issues. However, this is only one part of a broader article on consciousness. I now want to develop my treatment of introspective evidence, and its relation to objective (behavioural and physiological) evidence, for a second article. To help with background, I would be very grateful for good references to historical discussions (by psychologists) of introspective evidence (or ‘subjective reports’ or ‘phenomenology’). I would be particularly interested in pieces that touch on the thorny issue of what forms of ‘empirical’ evidence count as ‘scientific’.

-- Anthony I Jack (a.jack@ucl.ac.uk), April 19, 2001

Answers

Big question. Let me start with the part of the question about "empirical" evidence at the end, because I think it is, as you say, very thorny. The key problem (though by no means the only one) is that "empirical" means (has meant) different things to people in different disciplines and different historical periods... or to put things more precisely, everyone agrees that "empirical" means, loosely speaking, "pertaining to (sense) experience," but people have taken very different implications away from that phrase. Most scientists, I think, are more or less realists about the things they study. The reason they cleave so closely to "the observable" is that they make the (unargued) assumption that what is observed is what is "real," "objective," and the like. But philosophial empiricism (of which, one could argue, "empirical science" is but an applied branch) has historically sliced things up a little differently.

Under John Locke's empiricism, experience was intended more broadly than today. Indeed, I would think that the evidence of "introspection," liberally construed, would have counted as empirical evidence for Locke. With Bishop Berkeley, however, some of the more radical conqesuences of empiricism began to be drawn out. Taken strictly, empiricism means that the object observed is *nothing more* than the senstation itself (Principles of Human Knowledge, sec. 5, removed from second ed.). In short, Berkeley was something of an anti-realist about there being a thing-in-itself (to borrow a Kantian term) "beyond" the observation. Hume, too, called into question "common sense" features of the world that escape observation -- most famously "cause." Kant tried to piece this all back together, but by the mid-to-late 19th century phenomenalist scientist-philosophers in Germany and England -- most notably Ernst Mach -- were arguing that science is just about finding patterns of relations among observations, not about real objects in the world at all. Today "empiricism" in philosophy is almost synonymous with (at least a certain amount of) anti-realism (see, e.g., Bas Van Frassen's _The Scientific Image_, 1980). Scientists, however, tend to use the word in a very loose way, as a kind of "motherhood clause" (e.g., "As a good empirical scientist, I...), even though they typically (though not universally) believe in the reality of all kinds of theoretical entities that are *in principle* beyond observation -- e.g., subatomic particles (that is, they are not really empiricists, strictly speaking, at all).

So, when you distinguish in the way that you do -- in the way that psychologists typically have for the past century -- between "empirical" evidence and "introspective" evidence, you court a peculiar kind of paradox. John Locke, the consummate British empiricist, would, I think, have hardly have been able to make sense of the distinction. They both refer to personal, subjective (though possibly "inter-subjective") experience.

There's a ton more to say about this. I haven't really done it justice in this short (but still too-long) reply, but I hope I've been able to point you in some interesting directions.

-- Christopher Green (christo@yorku.ca), April 19, 2001.

Hi Anthony, don't forget to check out Ken Lloyd and his treatment of the 'Say-Do' problem while your in this topic area. Best, David

-- david clark (doclark@yorku.ca), April 19, 2001.

Dear Christopher Green, Thank you very much for your response. I was indeed intending to allude to the tension which you highlight. The current situation, that scientists who put weight on being 'emprical' tend to dismiss all forms of introspective evidence, looks peculiar in a historical/philosophical context. I take it that the critical turning point came with the Vienna circle, verificationism, Logical positivism and Wittgenstein's work. As far as I understand it, the thought was that to talk about something meaningfully, the 'language community' must all have some access to it - thus enabling them to verify the claim made. I think the thought was that private experience was not publicly available, and so, according to the hardest line, talking about it was simply meaningless. According to this verificationist line of thought (which many, e.g. Ned Block, are highly unsympathetic to), the point you make about experience needing to be 'inter-subjective' becomes critical if we are to save any reference to internal states as meaningful. However, the scientific community appears not to have been subtle and/or determined enough to hold out for such a solution. Instead, behaviourism appears to have grown from this philosophical school of thought, and so experimental psychology decided to thrown out any and all uses of introspective evidence.

-- Anthony I Jack (a.jack@ucl.ac.uk), April 20, 2001.

Anthony I Jack wrote:

"I take it that the critical turning point came with the Vienna circle, verificationism, Logical positivism and Wittgenstein's work."

The rejection of introspection among psychologists actually started prior to the founding of Logical Positivism. Watsonian behaviorism came as early as 1913, whereas Logical Positivism's heyday was the 1930s. According to the Encyclopedia of Philosophy, the verifiability principle was first formally articulated in Friedrich Waissman in 1930, though it had antecedents in Schlick's _Allgemeine Erkenntnislehre_ (1918) and Carnap's _Aufbau_ (1928). Wittgenstein's _Tractatus_ (1922) was also obviously influence.

Anthony I Jack wrote:

"Instead, behaviourism appears to have grown from this philosophical school of thought, and so experimental psychology decided to thrown out any and all uses of introspective evidence."

*Logical* behaviorism (of, say, the early Carl Hempel) grew out of logical positivism, but both Watsonian behaviorism and Pavolv's "reflexology" came earlier. In addition, it turns out that there wasn't as much contact as is widely thought between the logical positivist philosophers and the neo-behaviorists (Tolman, Hull, Skinner). An excellent account of this (lack of) relationship is Laurence D. Smith's _Behaviorism and Logical Positivism: A Reassessment of hte Alliance_ (Stanford, 1986). Indeed, my reading of the neobehaviorists is that, to the degree that they were familiar with the philosophical issues involved at all, they were influenced more by the 19th-century positivists, especially by Mach, than by 20th century logical positivism. There is some material on this in my 1992 article, "Of Immortal Mythological Beats: Operationism in Psychology" (available on-line at http://www.yorku.ca/christo/papers/operat.htm).

-- Christopher Green (cgreen@chass.utoronto.ca), April 20, 2001.

Thank you again. The references and dateline information are very useful in patching together a picture.

Are you confident that it is correct to identify behaviourism as the reason for rejecting introspective evidence? Watson was not so dismissive as is usually thought - indeed he actually supported the use of verbal reports (as discussed in the historical review of Ericcson & Simon's classic on Verbal Protocols). I would be interested if you knew of anyone else who wrote arguing against the use of introspective evidence. On the other hand, I can well imagine that no-one actually formally defended the rejection of introspective evidence - but rather that Watson's argument became more crude in the fading memory of psychologists, and other, more dominant, paradigms encouraged a different perspective. I notice another posting in the discussion group: "Well, to me, I greatly appreciate the efforts made by experimental psychologists in making attempts at quantifying, controlling, and manipulating behavior under study. I believe that this is a great milestone away from the "introspection" orientation to turn psychology into a more objective discipline. -- Shirley Lao (laosx@yahoo.com), March 31, 2001." I wonder why so many people implicitly assume that introspective evidence (which can be quantified) and objective evidence (admittedly often easier to quantify) are mutually incompatible. Is this just an historical accident - a result of the dramatic shift from introspectionism to behaviourism?

-- Anthony I Jack (a.jack@ucl.ac.uk), April 21, 2001.

Anthony I Jack wrote:

"Are you confident that it is correct to identify behaviourism as the reason for rejecting introspective evidence?"

I don't think I'd put it quite this way. The reasons then current among some psychologists -- especially comparative psychologists -- for rejecting introspection led to the rise of behaviorism. There's an excellent set of volumes edited by Robert Wozniak that document the rise of behaviorism. As I recall, Wozniak's introductory chapter shifts emphasis away from Watson, arguing that there was a large number of intellectually related researchers involved at roughly the same time. The main difference was that Watson had control of _Psych. Review_, the most prestigious psychological journal of the day.

"Watson was not so dismissive as is usually thought - indeed he actually supported the use of verbal reports (as discussed in the historical review of Ericcson & Simon's classic on Verbal Protocols)."

I guess it depends on how you read him. I read him as being pretty dismissive. There's a profound theoretical difference between the way he regarded verbal protocols (as just another "surface" behavior of approximately the same significance as, say, a cough or sneeze), and the way introspectionists regarded them (as accurate reports of "internal" mental states).

"I would be interested if you knew of anyone else who wrote arguing against the use of introspective evidence. On the other hand, I can well imagine that no-one actually formally defended the rejection of introspective evidence..."

Opposed to introspection, you might look at:

Dunlap, Knight. (1912). The case against introspection. Psychological Review, 19, 404-413.

In favor, you might look at:

Titchener, Edward B. (1898a). The postulates of a structural psychology. Philosophical Review, 7, 449-465.

Titchener, Edward B. (1912). The schema of introspection. American Journal of Psychology, 23, 485-508.

Titchener, Edward B. (1914). On "Psychology as the behaviorist views it". Proceedings of the American Philosophical Society, 53, 1-17.

Calkins, Mary Whiton. (1906). A reconciliation between structural and functional psychology. Psychological Review, 8, 61-81.

Calkins, Mary Whiton (1908c). Psychology as science of self. III: The Description of Consciousness. Journal of Philosophy, Psychology and Scientific Methods, 5, 113-122.

Al of these are available on-line at "Classics in the History of Psychology" (http://psychclassics.yorku.ca/)

-- Christopher Green (cgreen@chass.utoronto.ca), April 21, 2001.

I wonder why so many people implicitly assume that introspective evidence (which can be quantified) and objective evidence (admittedly often easier to quantify) are mutually incompatible. Is this just an historical accident - a result of the dramatic shift from introspectionism to behaviourism?-- Anthony I Jack (a.jack@ucl.ac.uk), April 21, 2001.

Sorry for responding to you so late. I believe that people have different definitions of "objectivity". These are two notions of objectivity: ontological and epistemologic.

Allow me to quote two excerpts from the following:

Bell, D. 1992. Objectivity. A Companion to Epistemology. J. Dancy and E. Sosa. Oxford, Blackwell: 310-312.

"there is a straightforwardly ontological concept: something is objective if it exists, and is the way it is, independently of any knowledge, perception, conception or consciousness there may be of it"

"There is, on the other hand, a notion of objectivity that belongs primarily within epistemology. According to this conception, the objective/subjective distinction is not intended to a mark a split in reality between autonomous and dependent entities, but serves rather to distinguish two grades of cognitive achievement...... Here objectivity can be construed as a property of the contents of mental acts and states."

To my understanding (correct me if I am wrong), some people adopt the ontological notion of objectivity in explaining the unobservables and consciousness through introspective method.

-- Shirley Lao (laosx@yahoo.com), April 26, 2001.