No one knows how much the government can borrow

It's a quirk that we use "debt" in the form of T-bills instead of printing more dollars. The t-bills get used and exchanged like money anyway. They do let the US have some control over the interest rates used in the rest of the economy, so it's not a useless quirk, but it's important to understand that US debt is nothing at all like personal debt, and it's probably defective to use the same word.

A couple other interesting outgrowths from that premise:

- the Federal Jobs Guarantee concept, which in addition to any positive externalities of putting the under-employed to work, also pegs the value of the dollar to labor (@$15/hr, $1=4min), while also providing a negotiating BATNA for the working class with their private employers.

- Because money is printed into existence, rather than an empty ritual of collecting revenue before spending it, taxation exists only for money to exit the system, reducing inflation and creating demand for dollars; tax payments aren't used to pay for anything, and are effectively burned. Kelton also makes an interesting point: rather than taxes being a "necessary evil" policy to pay for some other good, they can actually be reconstrued as positive goods in and of themselves: to price externalities (pollution tax) or discourage behavior (sin tax), etc.

The strongest argument against MMT, regardless of its theoretical merits, is simply the practical one: that Congress already perpetrates vast quantities of graft and fiscal short-sightedness, and it's unwise to trust such a transparently corrupt and dysfunctional institution with additional leeway for limitless spending.

https://youtu.be/2ONGvkAoOI0?t=1550

- it only applies to the US

- depends on having a hegemonic currency (i.e. everyone else earns in your currency and has to convert it, so that you can run a deficit and others supply the capital to fill it)

- contingent on control of the house, senate, and presidency, for about 3 terms in a row, to do all the things you want to do (in the MMT program)

- though sure, we could spend more on stuff we care about; we're not at "capacity" yet.

- you've already got a bond market in the US... why do do we need to re-invent everything in the world when the bond market allows you to already do it?

- hardly any other country actually sets their own monetary policy because the dollar is so dominant. When the fed goes up or down, it's effect is global.

- since every country has to import, if you print a lot of money, you'll get inflation through exchange rates & the import channel

Haven't listened to this one yet: https://youtu.be/NfKiW0Gfn04

If nothing else, please takeaway that MMT is a _framework for economic analysis_. You can apply it to any economy, you can use it to look at any policy decision, and you can work with this tool if you're a conservative or progressive. I find a lot of value in using it to understand China, Japan, emerging markets, economic history, etc.

With relation to the original topic, the answer through an MMT lens is very simple. Nominally, there's no limit.

A cornerstone idea of MMT is that a currency issuer can always purchase anything for sale in the currency that it has a monopoly over. Examples of these monetary sovereigns include the US, the UK, Japan, Australia, China. It does not include the EU, or most emerging markets (who effectively use another government's currency).

The implication of this is that a monetary sovereign government has no binding constraints on the amount of debt it can issue (it can of course issue debt to itself if no-one else is around to buy it, i.e. Treasury -> Central Bank).

Now that's not to say that government borrowing has no real limits. The most useful constraints to look at are real resource constraints (possible supply of goods and services), and external constraints (do you need to pay something in a currency you can't control?). If the government is purchasing more goods or services than the resource constraints are available to supply, you'll see an appreciation of prices (inflation).

Simply creating more dollars doesn't lead to inflation. Fiat currencies are just units of account (think score points), not some kind of commodity. Japan's money supply has quintupled since 1990 to 2020 (from memory), while the consumer price index has been roughly flat, and the USD/JPY exchange rate has been roughly rangebound (wide range, but not a monotonic increase like one would expect if using intuition )

Rushed for time, but happy to discuss/debate points of contention.