The row between the fact checking websites and Medicare-for-all supporters has continued over the past couple weeks. I briefly weighed in to point out that, studies aside, it’s difficult to estimate the cost because it’s impossible for us to know what level of healthcare spending will, in the long-run, be politically acceptable. The attempts to get an estimate all involve assuming particular levels of spending ex ante. The Republicans can claim that we would need to continue spending 18% of GDP, but they don’t know. Bernie Sanders can claim that we would be able to impose Medicare’s level of compensation, but he doesn’t know. Just like in other countries with systems like this, the level of expenditure would constantly be up for political renegotiation. Britain spends 7% of its GDP on its National Health Service. Will we spend 7% or 18% or somewhere in between? Anyone who tells you that they know for sure is lying.