Economic ideology mainly focused on the idea that there should be one single tax, a land value tax, with the surplus used to fund a basic income.
Henry George's book Progress and Poverty was one of the most widely-read books of the late 19th century, and profoundly influential on many people who would be prominent in the 20th.
The Henry George Theorem (named after, not by, George), states that investments in public goods will increase aggregate rents by at least as much as the cost of the investments. That is, unless funded by LVT, most of the value of public investment is captured by landowners.