There are limits to how high taxes can go, before the point is reached where higher rates of tax reduce the government's receipts
This is a different question from asking about the mix between government and private economic activity (3.2.3).
There is a theoretical limit on how much tax can be levied, as illustrated by the 'Laffer curve'. A YouTube video, The Laffer Curve, Part I: Understanding the Theory, explains the concept: total government income from a tax initially increases in proportion to the tax rate applied, but receipts start to level off as people take evasive action or reduce their effort. The curve then shows that government revenue starts to fall as the tax rate is further increased and the avoidance effects become dominant. No-one would do any work if the tax rate were 100%, so the government revenue would be nil.
The Laffer effect, though, only applies if tax rates are set very high. An analysis of the Laffer effect can be found in Samuelson and Nordhaus’s book Economics (pp. 313-316), which argues that American tax rates at the end of the 20th century were set low enough for the Laffer effect to be irrelevant: reductions in tax rates simply reduced revenues almost proportionally, whilst having no detectable impact in generating growth. The Economist argued that “The Laffer curve exists in principle, but the sweet spot is hard to find” and that President Trump's tax cuts in December 2017 simply increased America’s national debt.
The more practical limits to how high taxes can go is their effect on growth: if people don’t have money to spend there is insufficient demand for wealth to be created, and the total tax revenues shrink as the economy contracts. This is a Keynesian argument, which is briefly described in Samuelson and Nordhaus’s book Economics (p. 603). It applies most directly to taxes on low-paid and middle-income people: tax cuts for these people stimulate growth, whereas tax increases can be used to dampen growth and thereby reduce the risk of inflation (3.3.8.3).
(This is an archive of a page intended to form part of Edition 4 of the Patterns of Power series of books. The latest versions are at book contents).