The Explanation of Explanations

Aspects of Scientific Explanation by Carl G. Hempel

In 1965 Carl Hempel sought to describe the process of scientific explanation.  While it may not sound like an original or important thing to do, it was.  For now you'll just have to trust me because I'm the sort of person that electively reads books entitled Aspects of Scientific Explanation.

As you might guess, Hempel's account isn't exactly entertaining, nor is it intended to be, but it is the clearest and most organized account of the subject I know.  The Stanford Encyclopedia of Philosophy says that "recent discussion [of scientific explanation] really begins with the development of the Deductive-Nomological (DN) model. This model has had many advocates (including Popper 1935, 1959, Braithwaite 1953, Gardiner, 1959, Nagel 1961) but unquestionably the most detailed and influential statement is due to Carl Hempel."

Why is it important to describe or define scientific explanation?  Consider a recent article in The New York Times about the Catholic Church's revival of exorcism.  Here is a passage from the article:

"Some of the classic signs of possession by a demon, Bishop Paprocki said, include speaking in a language the person has never learned; extraordinary shows of strength; a sudden aversion to spiritual things like holy water or the name of God; and severe sleeplessness, lack of appetite and cutting, scratching and biting the skin.  A person who claims to be possessed must be evaluated by doctors to rule out a mental or physical illness, according to Vatican guidelines issued in 1999, which superseded the previous guidelines, issued in 1614."  Progress?  ("Not knowing what to do, we ape our ancestors; the churches stagger backward to the mummeries of the dark ages." --Ralph Waldo Emerson)

Devil possession is a way of explaining the symptoms listed above.  A particular mental illness would be another way.  The explanation that you credit has serious implications for what you do about the problem.

Everybody attempts to explain stuff to themselves and others every single day, and arguments about the validity of various explanations are plentiful in a society with the right to freedom of expression.  The senators from Oklahoma don't believe that global warming is explained by the greenhouse effect--whether they're right or they're wrong, their opinion means something significant in the computation of our national response and therefore means something for the fate of human beings on earth.

If everybody better understood how scientific explanation works, it might help to settle these arguments rationally over the validity or type of various explanations and theories (explanations and theories are much the same thing).  Hempel provides criteria by which one might assess an explanation; one could ask whether an explanation had a scientific character or not or whether it was really an explanation at all versus a different ideational product of the mind.

I was introduced to Hempel and also Hans Reichenbach while researching the scientific validity of psychoanalysis, about which endless debates rage and roar over whether it's science or "pseudo-science."  Like Reichenbach, Hempel suggests that knowledge is generalization from repeated instances (Francis Bacon's "induction by enumeration") and that explanation seeks to define specific observed relationships as instances of general relationships established in principle.  Hempel says of psychology, "[W]hile frequently the regularities invoked cannot be stated with the same generality and precision as in physics or chemistry, it is clear at least that the general character of those explanations conforms to our earlier characterization."   He makes a similar argument regarding the study of history, asserting that good historians explain historical events on the scientific deductive-nomological model, but of necessity with less than mathematical precision.  To denote the somewhat lesser degree of precision, he calls historical explanation an "explanation sketch," which is "scientifically acceptable" since further research can confirm or disconfirm it.  Says Hempel, "Explanation sketches are common also outside of history; many explanations in psychoanalysis, for instance, illustrate this point."  So ... stick that in your Popper and Karl it.  With Carl Hempel on your side, you too can win arguments staged in Goodreads reviews of books that are out of print and unrated.  But at least you yourself will know.

The Relevance of Psychoanalysis

Introductory Lectures on Psychoanalysis by Sigmund Freud

Neuroscientist Eric Kandel, who won the Nobel Prize in Medicine in 2000 for his research on the neurochemistry of the Aplysia sea slug, wrote in 1999 that “psychoanalysis still represents the most coherent and intellectually satisfying view of the mind.”

That may come as a surprise to people who think of Freud as a relic or a quack, and there are many who feel that way, and with a passion; I've learned that Sigmund Freud, like politics and religion, is a dangerous topic of conversation.  But Eric Kandel’s 1999 paper, “Biology and the Future of Psychoanalysis: A New Intellectual Framework for Psychiatry Revisited,” ought to give some pause at least to anyone who despises Freud without having carefully read and considered his ideas.  Kandel’s paper opens like this:

“During the first half of the twentieth century, psychoanalysis revolutionized our understanding of mental life.  It provided a remarkable set of new insights about unconscious mental processes, psychic determinism, infantile sexuality, and, perhaps most important of all, about the irrationality of human motivation.”  Kandel, American Journal of Psychiatry 1999; 156:505.  Or, to put it more simply, it provided insights into the relation between what you feel now and what happened in your childhood, even if you can't remember it clearly, and insights into dynamic relationships in the mind between desire, love, anger, loss, guilt, fear, and the lies we tell to ourselves to make it all feel better.  Finally it made the point that talking about it (aka psychotherapy), and in so doing coming to look at yourself truthfully, is a real help.  These ideas are so deeply subsumed into our culture that they're almost clichés at this point.

Yet canards, misconceptions, and prejudices against Freud abound, and many could be cured if Freud-haters actually read the brilliant and brilliantly written Introductory Lectures on Psychoanalysis from beginning to end, carefully, and with an open mind.

The British empiricist Karl Popper (who Ludwig Wittgenstein famously threatened with a fire poker) believed that psychoanalytic ideas were not only unproven but unprovable; he thought there was no way to evaluate the truth or falsity of a psychoanalytic proposition because psychoanalysts interpreted data in such a way that any and every possible finding would be consistent with their theories.  (Some physicists have said as much about "string theory," by the way.)  Popper's view is a common one, partly because Freud and the psychoanalysts who followed have sometimes treated doubters as patients and doubt of Freudian theory as a symptom (called "resistance").  While emotional "denial" and "resistance" are real phenomena, worthy of study and recognition, it seems like a bad strategy to forestall healthy intellectual skepticism in this way.  Kandel argues that despite the tricky nature of the emotional and cognitive phenomena that psychoanalysts study, they have to do a better job demonstrating the validity of their findings in the methodological terms with which most scientists are familiar.  He's right.  If not, psychoanalysis insulates itself, prevents others from reaping its benefits, and prevents itself from reaping the benefits of advances in other fields of study, like psychopharmacology.

Psychoanalysts do, of course, base their theories on close observation, and their interpretations are no different in syllogistic form from other scientific interpretations.  For example, we know the core of the earth is made of iron and nickel even though no one has ever seen the core of the earth directly; scientists have interpreted seismic wave patterns as signs of the presence of iron and nickel, just as psychoanalysts identify conscious and unconscious ideations by signs--mainly, words.  You might say to a psychoanalyst, "I feel worried but I don't know why."  You are conscious of part of the contents of your own psyche, but perhaps not all of them.  You talk more and in the raw material generated by your talking you discover clues--signs--of the full nature of your worries.  You find yourself talking about your health a lot.  You are worried about your health, you've been having chest pains...  It occurs to you that you are turning 52 years old this month...  50 was the bigger milestone, but you had no worries at the time of your birthday two years ago...  You read an obituary about a famous lawyer.  Your father was a lawyer who died, it occurs to you, of a heart attack at age 52...

Maybe you could care less about your own inner life.  If you can get away without examining yourself, then you're lucky.  For the rest of us, there's Sigmund Freud.

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