  I argue that some important elements of the current cosmological model are
"conventionalist" in the sense defined by Karl Popper. These elements include
dark matter and dark energy; both are auxiliary hypotheses that were invoked in
response to observations that falsified the standard model as it existed at the
time. The use of conventionalist stratagems in response to unexpected
observations implies that the field of cosmology is in a state of "degenerating
problemshift" in the language of Imre Lakatos. I show that the "concordance"
argument, often put forward by cosmologists in support of the current paradigm,
is weaker than the convergence arguments that were made in the past in support
of the atomic theory of matter or the quantization of energy.
