Lost In Translation? Part II: Kuhnian Incommensurability

In part I we saw that the partisan incommensurability many CAM proponents and apologists like to invoke is vacuous: self-refuting.  Therefore, it should not be surprising that this does not figure in the philosophy of Thomas Kuhn; it only appears as a straw man in the work of Kuhn’s critics: or a facile philosophical redoubt for those who want an excuse to believe in the demonstrably false.

Are there other sorts of incommensurability? Yes, there are; philosophers have identified many different versions of this idea (for example, see here and here).

It is only under the unsupportable scheme of complete incommensurability that communication, and hence comparison, between ‘paradigms’ impossible; in the others it becomes a matter of translation.

So what sort of incommensurability did Kuhn argue for?  This has been debated by expert philosophers for many years.  What follows is my own amateur summary of the ideas Kuhn elaborated in SSR.  As usual, page numbers to the third edition (1996) appear in square brackets.

Incommensurability makes its first substantial appearance in chapter IX: “The normal-scientific tradition that emerges from a scientific revolution is not only incompatible but often actually incommensurable with that which has gone before.” [p.103].

At this stage in the discussion it is not altogether clear what type of incommensurability Kuhn has in mind.  However, this passage does not insist that all normal-scientific traditions are incommensurable with their forebears.

There is certainly a global aspect to Kuhn’s view; striking a parallel with gestalt switches (like the famous duck/rabbit) he proposes that: “Only after a number of such transformations of vision does the student become an inhabitant of the scientist’s world” [p.111]. If the trainee is to be inducted into his world of science, “he must learn to see a new gestalt”: the result is, “the world of his research will seem, here and there, incommensurable with the one he had inhabited before.” [p.112]

Another, more moderate version is nestled alongside his global incommensurability:  a local one; incommensurability appears, “here and there“: not everywhere.

When Kuhn moves on to discuss the resolution of scientific revolutions his incommensurability is clearly partial and more than just semantic [pp.148-149].  For example, he identifies incommensurability as the reason, “why the proponents of competing paradigms must fail to make complete contact with each other’s viewpoints”.

The nature of paradigmatic disagreements goes beyond language.  It encompasses which problems “any candidate for paradigm must resolve”, includes standards (or definitions) of science, the meaning of and relationship between terms, concepts and experiments.

The failure to communicate is not just about sense and meaning; during a revolution, for Kuhn, “the whole conceptual web” is “shifted and laid down again on nature whole.”

Although he seems here to be espousing a kind of global incommensurability once more, it is not an impenetrable barrier:  “proponents fail to make complete contact” and, “Communication across the revolutionary divide is inevitably partial.” 

Next Kuhn moves on to, what he calls, “the […] most fundamental aspect of the incommensurability of competing paradigms”: that their, “proponents […] practice their trades in different worlds.” [p.150]

Again, this underlines that at this stage in his career the incommensurability of scientific paradigms was indeed global.  However, it’s not a relativist position:

“Practicing in different worlds, the two groups of scientists see different things when they look from the same point in the same direction.  Again, that is not to say that they can see anything they please.  Both are looking at the world [this must now be the natural world, rather than the different paradigmatic worlds they are alleged to inhabit], and what they look at has not changed.  But in some areas they see different things, and they see them in different relations to each other.” [p.150]

Regardless of which ‘paradigm’ they inhabit, scientists views are conditioned by what they observe in the unchanged (natural) world.

It is also clear that Kuhn mixes global incommensurability with a local kind: “in some areas they see different things”.  I’m not at all convinced that this is valid; if you live in different worlds then surely everything is different?  If they can be mostly the same, then why invoke this metaphor?  Surely the image of inhabiting different countries would be more apt? (It is interesting to reflect that in his later years Kuhn reformulated his incommensurability as a local property.)

In 1969 Kuhn published a Postscript to SSR.  In it he sought to correct, “gratuitous difficulties and misunderstandings” [p.174].  As part of this effort he sought to clarify his position on incommensurability and theory choice.  He summarised his position in these terms:

“I have argued that parties to such debates inevitably see differently certain of the experimental or theoretical situations to which both have recourse.  Since the vocabularies in which they discuss such situations consist, however, predominantly of the same terms, they must be attaching some of those terms to nature differently, and their communication is inevitably only partial.  As a result, the superiority of one theory to another cannot be proved in the debate.  Instead, I have insisted, each party must try, by persuasion, to convert the other.” [p.198]

Gone are ideas about different worlds; replaced by something which seems more like semantic incommensurability.  Nevertheless, communication is not totally blocked: it is partial. 

Also, this should not lead to disengagement; with both sides pulling away from each other to allow separate conflicting ‘paradigms’ [by this point re-cast as disciplinary matrices] to co-exist in the long term.  Rather, each party must try to persuade the other to their view.

This, after all, is science: the quest to determine the best description of nature, not negotiate a political compromise or ignore anomalies.  It is this insight which provides the proper context for dismissing the use of the incommensurability gambit by CAM advocates.  Their plea to ‘leave us alone so we can continue to ignore the contradictions within our world and take money from the public purse’ places them in a position where an appeal to the philosophy of science is entirely inappropriate.

It is also important to note that when Kuhn talks here of “proof” it is, “logical or mathematical proof.”  Scientists are completely comfortable with the idea that theories cannot be proven by formal logic or mathematical manipulation.  Those of a falisificationalist persuasion don’t talk about proof, but the survival of theories in the face of stern testing.  Whatever their philosophical leanings, scientists are overwhelmingly happy to view current knowledge as provisional, always open to improvement.

Kuhn then moves on to insist that, “philosophers have seriously misconstrued the intent of these parts of my argument.”  His summary of this misrepresentation strongly evokes the philosophically illiterate use of these ideas by CAM apologists:

“the proponents of incommensurable theories cannot communicate with each other at all; as a result, in a debate over theory-choice there can be no recourse to good reasons; instead theory must be chosen for reasons that are ultimately personal and subjective” [p.199].

This is an interpretation that Kuhn flatly rejects.  I wish all those CAM practitioners who lazily write, “(Kuhn, 1970)” straight after espousing this kind of complete incommensurability would actually do the man the service of reading what he wrote.

How did Kuhn think that the process of persuasion could be carried out?  First, he outlines what he considers are the real difficulties; those involved in this kind of scientific dispute, “employ the same vocabulary” and therefore, “must be using words differently” [p.200].

However, their difficulties will, “not be felt in all areas of […] their scientific discourse” but will, “cluster most densely about the phenomena upon which the choice of theory most centrally depends.”  Here we can see that Kuhn’s incommensurability is becoming more of a local property.

Since scientists (contrary to some speculation) are all human, inhabit the same physical world and share a common profession Kuhn notes, “Given that much in common, they should be able to find out a great deal about how they differ.”

With this common background they can, “recognize each other as members of different language communities and then become translators.”  This is not an easy task.  Accepting the ‘language’ metaphor, anyone who has ever tried to translate from their mother tongue to a different language realises that the task reaches beyond vocabulary and grammar to encompass shared cultural references and style.

Nevertheless, although this may be a difficult process, it is often accomplished both in literature and, metaphorically, science.

So, Kuhnian incommensurability (in the context of SSR) does not prevent communication and rational theory choice.  It ends up being partial and local in character.  Overcoming it is a matter of translation, an imperfect but an entirely viable and rational process.

I think that Kuhn scholar Rupert Read summarises Kuhn’s legacy eloquently, “he advocates something profound but modest: an attempt to understand what it is that is lost if one translates (say) one paradigmatic theory into the terms of another.”

Kuhn does not provide a fairly-tale castle, where gentle souls can comfort themselves with nonsense, safe from the ogre of reality.

Conclusions.

So what conclusions can we safely draw from this epic journey?  Well, I would suggest never accepting protestations of complete incommensurability: Kuhn never made them and they are self-refuting. These are merely excuses.  If they are made, ask what philosophical work they are based on.  If anyone says, “Kuhn”: ask them to actually read his work before relying on it!

To be fair, if you come across a criticism of Kuhn, make sure it’s not directed against the straw man of complete incommensurability.

It is also helpful to reflect that Kuhn was actually talking about how science progresses.  His philosophy was based on a study of the history of science.  The clue is in the title of the book I’ve been rambling on about, The Structure of Scientific Revolutions.  Application of this philosophy to other non-scientific disciplines is, of course, possible but must be justified.

Just quoting Kuhn and going on about ‘paradigms’ doesn’t mean that a particular branch of knowledge shares enough in common with science to make the application valid.  I certainly think that homeopathy is a good example of a ‘discipline’ that does not share enough of the character of science to justify recourse to Kuhn.  I suspect that trying to justify the application of a Kuhnian structure to much of the world of CAM would have similar difficulties.

It’s worth re-stating that Kuhn’s comments on theory-choice are about comparing science with science.  Nothing in Kuhn concerns the comparison between science and non-science. For Kuhn, a revolution replaces one scientific paradigm [disciplinary matrix] with another: there is no long-term co-existence. His work is about how science progresses: not trying to parcel off ideas and protect them from that progress.

Are there any bits of Kuhn’s ideas on incommensurability and theory-choice that I don’t agree with?  Yes, I’m no Kuhnian.  A weakness of his historical analysis is that it assumes that the future ‘structure’ of science will look like that of the past.  Given the upheavals in science, society and industry that have happened since the 1960’s I have my doubts as to the validity of that assumption.

Also, as Sokal and Bricmont have pointed out, just because a particular theory-choice may not have been made for the most objective reasons at the time; it does not mean that we should overlook the way successful theories accumulate good objective evidence in their favour as time passes.

Thinking about the language metaphor that Kuhn relies on to describe scientific theories and the communities that embrace them, makes me think about the way that scientific theories and languages differ.

When comparing scientific theories and deciding which to choose, it  is usually a choice between the old and new.  Their communities of supporters are not necessarily geographically separated.  On the other hand, languages commonly develop along side each other within communities that are, necessarily, geographically separated.

So what would I like to say to CAM advocates who would still persist in playing the incommensurability gambit, even in the absence of support from Kuhn?

Simply, that the proof of the pudding is in the eating.  We all live in the same physical world; we all want a long, healthy, disease free life.  This makes available to us common units of measure: the presence of virus, bacteria or tumours in our bodies and ultimately death. 

CAM advocates need to get real; stop this silly pretence that somehow, by the magic of philosophy, they are not living the same natural world that the rest of us are.