Solar dynamo theory has experienced arguably three major paradigm shifts
since its broad initial acceptance during the 1970s.
Inevitably, these paradigm shifts have brought the modelling further away
from the original ideas that were based on dynamo theory.
At the same time solar dynamo theory has lost much of its
initial rigor that dynamo theory used to be based on.
It its therefore important that the motivation for such departures
from the original theory are well justified.
In the following we comment briefly on each of the three paradigm shift.

In the Sun an oscillatory magnetic field is generated, but new research
now shows that at large magnetic Reynolds numbers this can only happen
if the Sun sheds small-scale magnetic twist through the surface while
regenerating an interlinked assembly of large-scale poloidal and toroidal
magnetic fields. The Sun is believed to accomplish this through coronal
mass ejections, which are known to shed approximately the required amount
of magnetic twist or helicity.

The inclusion of the effects of coronal mass ejections into the model
is believed to be one of the key factors of future solar dynamo models.
Other factors include the recently discovered near-surface shear layer
of the Sun, where the shear has the opposite radial gradient than in
the bulk of the convection zone, and can lead to equatorward migration
of sunspot activity, which was another major problem in understanding
the solar dynamo. Finally, the discovery that convection pumps magnetic
fields downward and thus opposes magnetic buoyancy losses is another
factor that makes so-called distributed dynamo model viable. Here, the
magnetic field resides in the entire convection zone, and is thus not
confined to the thin layer just beneath the convection zone, which is
still assumed in many models.