Inflation is always and everywhere a monetary phenomenon.
- Milton Friedman
The hydra grew another head.... back to monetary policy. Here I think I'm on more solid ground. I'm not in total disagreement, but a single quote lacks nuance, and nuance is important.
Firstly, there There are heaps of quick articles online that show inflation that's not purely due to money supply. Wikipedia and investopedia will do.
Here's a type of inflation that deals with expectations :
https://www.investopedia.com/terms/w/wage-price-spiral.asp
Another phenomenon is 'stagflation' :
https://en.wikipedia.org/wiki/Stagflation this phenomenon includes a wage-price spiral, but also involves cost-push inflation.
Cost Push inflation also has little to do with money supply:
https://www.investopedia.com/terms/c/costpushinflation.asp
If you read enough of the Stagflation article , you'll notice that Keynes sometimes agreed with more monetarist interpretations, and Friedman with more psychological ones.
The inflationism of the currency systems of Europe has proceeded to extraordinary lengths. The various belligerent Governments, unable, or too timid or too short-sighted to secure from loans or taxes the resources they required, have printed notes for the balance.
John Maynard Keynes, The Economic Consequences of Peace (1919).
Hayek and Friedman would happily agree with this. They're all about the money supply (and long-term views).
If you understand what a Philips Curve is (here's a
very useful image, and
article) you'll understand the significance of the Stagflation article crediting Milton Friedman (and Edmund Phelps) with challenging the basic concept. They were saying it didn't take
expectations into account - which provided a chance to regain a kind of equilibrium (and go back to a situation a bit more consistent with monetarist views). That's a very psychological explanation for someone apparently devoted to money supply... and the answer, of course, is that Friedman was probably a flexible thinker (may he rest in peace). He was not necessarily as dogmatic as sometimes portrayed.
I don't think Keynes or Friedman were hypocrites, but dry-quoting someone (i.e. without context) is not a good idea when talking about a complicated topic.
One way both views can live somewhat symbiotically is regarding time. I'm quoting the wikipedia article on Stagflation again:
....while neoclassical and neo-Keynesian models are often seen as competing points of view, they can also be seen as two descriptions appropriate for different time horizons. Many mainstream textbooks today treat the neo-Keynesian model as a more appropriate description of the economy in the short run, when prices are 'sticky', and treat the neoclassical model as a more appropriate description of the economy in the long run, when prices have sufficient time to adjust fully.
There are disagreeing interpretations, and what emphasis is given to different models seems to be one of them. That gets lost in a quick quote.
This has very little to do with the OP... so:
@Jiben
Yes! I want to see inflation be a bigger deal (either through spiralling inflation from introduced bullion, or currency debasement) .
Make inflation great again (or terrible again - same thing really)! I demand currency crises!!!!
[edited to make things slightly more concise]