Sunday, February 12, 2012

Is Scientific Progress Cumulative or Revolutionary? Kuhn Part 1

Notes and Thoughts on Thomas Kuhn's The Nature and Necessity of Scientific Revolutions

Favourite Quote: "...whatever its force, the status of the  circular argument is only that of persuasion.  It cannot be made logically or even probabilistically compelling for those who refuse to step into the circle."


Kuhn's view of how science works is that in order for there to be scientific development, one scientific paradigm must be "overthrown" by a new mutually exclusive paradigm.  His position is in contrast to the view that science develops incrementally and cumulatively.  In short this is about whether scientific progress is best described as evolution or revolution. 

The Nature of a Scientific Revolution

Scientific revolution? Vas ist das?  Obviously, it's a revolution in which everyone wears lab coats.  Oddly, Kuhn has a different idea of what it means.  I want to skip though this part fairly quickly soz we can get to the meat of the issue.  Basically, Kuhn wants to drahr an analogy between political and scientific revolutions.  

Quick definition of terms:  by scientific paradigm, I mean an overarching theory upon which other sub-theories depend/are embedded.  Examples of paradigm theories are Newtonian physics, phlogiston theory, kinetic molecular theory, and, since it's Darwin day today (yay!) we should, of course, include evolution.  

The first parallel is that political revolutions are brought about by a growing belief by a portion of the population that the institutions don't adequately solve the problems that those institutions are designed to solve, and that often the institutions themselves partly contribute to the problem.  In short, substitute "paradigm" for every instance of "institution" and you have Kuhn's view of how scientific revolutions come about.  

The second parallel is that political revolutions are partly about changing institutions in ways that those institutions, by definition, prohibit.  So, for a revolution to be successful, the initial institutions must fundamentally change.  This implies (as we are seeing in Egypt, for example) that there will be a transition periode where it's not clear what institutions are doing the governing.  Will the pharaohs maintain power and continue to build pyramids or will the Muslims take over and build mosques?  

Uncertainty will prevail for a while but eventually, individuals will have to choose one set of institutions over another; and one set of institutions will become de facto.  During this period of uncertainty there will be mass campaigns of persuasion--often violent.  Again, substitue "paradigm" for every instance of "institution" and you get Kuhn's view of scientific revolutions.  

One last note is that, when we are talking about competing sets of institutions there is no objective standard to which we can appeal to choose one over the other.  The same goes for scientific paradigms. Kuhn' s not talking about cases where there's overwhelming evidence in favour of one theory, but cases where both paradigms can explain most of the phenomena it aims to describe.  The contention of one group is that the way that one paradigm explains things is be preferred.

To summarize, except for the fact that scientific revolutions are often more violent and bloody than political revolutions, Kuhn's basic analogy is that there are significant parallels between the two types.  The analogy will allow us to conceptualize in a more familiar way how scientific revolutions occur.  Also, these similarities will support his thesis that scientific process requires the destruction of existing theories by new theories; as opposed to the idea that scientific progress is cumulative--i.e., the old is simply modified by the new.
 Lets move on...

Changes in Scientific Paradigms that Support the Revolution Hypothesis 

So, the general situation we are discussing will look something like this:  there are 2 competing paradigms that are both capable of explaining most empirical observations.  We can't point to any particular evidence that favours a paradigm because the evidence is only intelligible within a given paradigm; for instance when I talk about electrons, I'm necessarily invoking the atomic model of matter (i.e., paradigm).  

The Problem of Circularity 

So, check it.  Suppose we lived in a pre-quantum mechanics era.  The standard atomic model is king of the wooooooooorld.  There's no quantum touch healing and no quantum energy healing.  People are dying everywhere.  In short, it's a horrible place.  Now, along come these crazy people that say that understanding matter within the standard atomic model is wrong.  We should consider electrons not to be particles but waves.  

Notice that we can't talk about electrons without pulling in all the rest of the stuff that goes along with the standard atomic model, and we can't talk about quantum energy waves without bringing in the rest of quantum theory.  

The prollem of cirkalairity arises because there isn't a one to one correspondence of terms when discussing competing paradigms.  The consequence is that any argument for a paradigm will necessarily presuppose that paradigm.  As Kuhn says 

"...whatever its force, the status of the  circular argument is only that of persuasion.  It cannot be made logically or even probabilistically compelling for those who refuse to step into the circle."

I'll esplain this in more concrete terms in a bit, but for now, it will suffice to say that cirkalairity is going to be a prollem when a proponent of one paradigm argues with a proponent of a paradigm from another mother.  

I lied.  One more thing about cirkalairity:  A further prollem that derives from the cirkalairity is that logic and empirical evidence alone will not be sufficient to persuade the relevant community toward a particular paradigm.  The obvious question then is, how is it decided when one paradigm gets replaced by another?  Do scientists arm wrestle over it?  Do the cleanest lab coats win?  How?

What About New Discoveries?

It's possible that a new discovery could push opinion one way or another but it's going to depend on the nature of the discovery.  Consider our paradigm about what is required in an environment for life to exist.  If life were discovered on the moon--an environment our current paradigm holds as hostile to (native) life--we'd have to change our paradigm.  But if life were discovered in the unknown reaches of the universe, we'd have to know more about that environment before our paradigm changed.  

Similarly, sometimes new discoveries connect previously unconnected theories.  This is the case with the theory of energy conservation which links dynamics, chemistry, alectricity, optics, and thermal energy.

In short, new discoveries do not guarantee support for one paradigm over another.  Sometimes they are compatible with both, inconclusive, or connect the previously unconnected.   

Importantly, new discoveries reveal something new about the natural order of the world, but do nothing to influence our decision regarding the preferred theoretical framework within which to describe the discovery.  

What About Science as a Cumulative Enterprise?

Why all this crazy talk about revolutionary overthrow of paradigms?  Kuhn's obviously just read too much Marx and Hegel.  Why can't we just say science is cumulative?  You know...we have a theory about something and then we discover something that doesn't fit our theory so we adjust the theory.  This happens over and over.  There are no crazy revolutions going on.  We just take new information in the context of what we know.  When we have to, we adjust our theory so it best fits empirical observation.  

Ok, says Kuhn, I'll grant this is true in normal research.   Scientists wearing lab coats choose for their research projects problems that can be solved with the concepts and instrumental techniques already and close to those already existence.  The direction of their research will be influenced by the phenomena their existing working model predicts or areas of the model that need to be filled in.  This is obvious enough.  Scientists don't just do random research.  There's always some expectation of result which is defined by the paradigm within which they work. 

The consequence of this is that anomalies will be rare to the degree that the working theory incorrectly predicts and/or the scientist incorrectly deduces and/or incorrectly uses his test tubes and bunsen burner.   Otherwise stated, it will be the amount of different types of anomalies and their inability to be assimilated into the prevailing paradigm that give rise to (hehe, I said "give rise") the issue of competing paradigms.  For the existing paradigm, the anomaly will be just that--an anomaly; but a new paradigm might redender the anomaly law-like.  

At some point, given enough or recalcitrant enough anomalies, a new paradigm will be proposed and the people in lab coats will have to decide to choose one or the other.  If they choose the new one, by definition they must reject the other.  Since the rejection of paradigms is what marks revolution, it is Kuhn's model that best describes how scientific progress is made, not the cumulative model.

A further point for Kuhn is that since two paradigms will have, by definition, different logical consequences, they will predict different things.  If the cumulative model is correct and we hold on to our old theory after we have accepted the new one, then we will have differing predictions from within the same scientific field.  But this isn't what happens (when there is consensus), the predictions derived from the new theory will crush the heads of the beliefs of the first, and so, the old theory is necessarily displaced by the new.  This is as opposed the the old theory assimilating the new, and science proceeding in a cumulative fashion.  

So, where we at?  Basically, Kuhn's argument is that scientific progress isn't cumulative but revolutionary.  It requires the rejection of previous theories by new ones, rather than the assimilation of the new by the old.   Part 2 coming up!

1 comment:

  1. You make it so easy to understand, thanks!