with the occasional clever argument for progressivism that the mainstream finds disagreeable popping up now and then and nudging things around.
So why aren't those arguments being used to defend progressivism today? The answer, which isn't hard to notice if you actually look at old progressive arguments, is that those arguments tend to have premisses that modern progressives no longer believe and their conclusions are also very different from modern progressive positions.
even though the reactionary and progressive ideologies don't seem to have changed significantly.
This is not the case as I mentioned above.
Has there been significant change in the underlying trends where reactionaries are pessimistic about inherent human nature, consider it basically impossible to change significantly, and consider the problem of developing social mechanisms to control it something vital to social stability that takes generations and centuries to solve and is likely to end up with constraining and unintuitive solutions which will nevertheless be the best bet available, while progressives are optimistic that human nature is either benign or malleable enough that it's possible ...
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Of course, for "every Monday", the last one should have been dated July 22-28. *cough*