Progress in science is a matter of developing theories
that are better than the existing ones. A new theory is better if it explains
phenomena that the old theory fails to explain, although they are within its
range and should have been explained by it. Or the new theory gives a more
plausible and simpler explanation of the facts. Of course, with the help of
some additional suppositions it may be possible to give the old theory a new or
broader basis, but with each additional supposition the old theory becomes more
complicated and by that more unlikely. The rule of thumb in science is the
simpler the better and generally it works that way. So, many old theories have quitted
the scene in exchange for new ones that played their parts better. Now we know
that the sun doesn’t orbit around the sun but that the opposite is the case. We
know that there is no ether that fills empty spaces but that a vacuum is really
possible. And we know now that life cannot originate from dead matter. How
progress works in science has been summarized by Karl Popper in a well-known
scheme:
P1 > TT > EE
> P2
In words: If we have a problem that we can’t explain with
the old theory (P1), we revise it or develop a completely new theory (TT). Then
we perform experiments (EE) in order to test our new ideas, and if the new
ideas are confirmed, the old theory has been improved or replaced in favour of the
new one. However, usually we see then new problems (P2) and the cycle starts again.
Since here in my presentation we start with the idea of a theory that appears
to have mistakes, we might describe the process of theory evolution also this
way:
TT1 > P > TT2
(tentative) > EE > TT2
Since TT2 is better than TT1 Popper talked here of
error elimination. This implies that actually the old theory has failed,
because it contained mistakes. But this is how scientific progress works and
there is no other approach. And often it is so that the old theory has been
used for a longer or shorter time to everyone’s satisfaction, despite its
mistakes.
TT1 can also fail for another other reason: Not because
it has been replaced by a better theory but because it is bad science. That’s
what we have seen in my last blog. If we look at the first scheme, then the
trouble is not that P that can’t be explained by TT but we think that TT has
explained P but the explanation is false. It is because the tests that seem to
substantiate TT have not been well done. So there is a failure in the
performance of EE. This can happen by accidental occurrences, but usually it is
so that the methods of investigation have not been well applied by ignorance,
negligence, lack of money or something like that, or in order to please the one
who pays the investigation or even by fraud. In other words, the tests failed
because of bad science. If it happens now and then it’s a blot on science.
However, if it happens too often and on a large scale, sooner or later it will
lead to a crisis. Then the schemes are no longer as shown above but they have
become:
P1 > TT > EE
> P2
and
TT1 > P > TT2
(tentative) > EE > TT2.
When the failures come to light we have a crisis in
science and the schemes as just represented stand for regress in science. And
that’s what we see now in social psychology. From a methodological point of
view the rules are simple: Besides a strict and correct application of the
methodical prescriptions any investigation has to be replicated, if possible by
other investigators in another setting and with another set-up. But often there
are many reasons not to replicate an “old” experiment. Practical reasons,
financial reasons and human reasons, for little credit can be gained by affirming
what has already been said by others (and if the original investigation has
been well performed, this will be the result). But a crisis in social
psychology does not hurt only social psychology itself (or any other science
that is hit by such a crisis, as the case may be), but it has wider
consequences. Results are applied. Convinced that the psychological investigations
have been well done, therapists have put their outcomes into practice. In
philosophy they have affected the view on man. Etc.
The key question is how it could come that far. If
we don’t give it an answer it can happen again, in psychology and elsewhere. There
is a name for the present problem: Replication crisis. It’s a name that points
already to its solution. But who will be prepared to tackle the problem, as
usually it is so that it doesn’t bring much to you if you do old wine in new
bottles?