Most people who have thought carefully about the risk-free interest rate realize that any real-world security provides merely an approximation to that ideal. The fact that people rarely describe t-bond rates using verbose but more accurate phrases such as "the nearest we can come to measuring the risk-free interest rate" doesn't tell you much about how many fail to see that it's more accurate. I haven't read Black Swan (but have read a prior book of Taleb's). I doubt typical investors ought to follow the advice you've quoted, but it seems plausible that some investors ought to. His description of treasury bills as extremely safe seems accurate enough for practical purposes. It only requires that investors be able to anticipate a U.S. government default / hyperinflation something like 90 days in advance (i.e. it's a good deal more reasonable than describing 30-year bonds as extremely safe). Good investing is mostly about avoiding big mistakes, not about perfectly avoiding all errors, and Taleb's advice would reduce one's risk by a big factor compared to most competing advice.

The problem with anticipating a default 30 days in advance is if other investors anticipate the same - it will be too late to unload.

I don't think investors actually believe there is zero risk - the phrase "risk-free" is a holdover from the assumptions of theoretical asset pricing models, and now everyone who gets trained in economics or finance is just being sloppy.

It would take more than the USA ceasing to exist for bonds to become worthless - maybe the USA will peacefully disincorporate, but still unwind all its debts. It would take something that would destroy the productive capacity of the USA as a whole, or something that causes massive tax revolts - an asteroid strike, or an alien invasion maybe? If you're an optimist about the economic effects of AI/nanotech etc, then it seems that should make the chance of defaults less likely, not more.

Eliezer, your use of the term 'risk free bonds rate' is confusing. There is clearly no such thing a risk-free bond, so the notion of a risk-free bond rate doesn't seem to make sense. True, it's not impossible to lose money in short treasuries, but this has nothing to do with what's more commonly known as the 'risk-free rate' in modern portfoio theory.

The 'risk-free rate' is simply shorthand used to refer to a particular input to modern asset valuation models. It says nothing about a given security's total inflation-adjusted return, nor is it a conclusion drawn from a given government's past default history. The interest paid on short treasuries is considered risk-free in the limited context of asset valuation simply because a government can theoretically print as much money as it needs to pay the coupon.

That said, you're also correct to point out that in English the descriptor 'risk-free' suffers from imprecision. But this is just what happens when the shorthand names for inputs to mathematical models bleed over into the vernacular. That is, from a semantic standpoint 'risk-free' doesn't mean risk-free.

And I can certainly appreciate your poke at Taleb for not explicitly acknowledging potential black swan events affecting short treasuries. But as you know, he assumes you want positive returns on your money and is suggesting what he sees as the most optimal balance between risk and return in a 100% invested portfolio. Not that he's right or wrong about any of it.

I believe Egan-Jones once downgraded US debt to AA because of our balance of payments problems and our rather irresponsible spending habits. I suppose Taleb's tactic would make sense if one of the Swans you were betting on was a treasury default.

You'd only assume a 10% risk given a 30 year bond over a 300 year future if you assumed an even risk distribution over the 300 years.

Eliezer, Your criticism seems a bit superficial (in that I think almost everyone already realizes that T-bills aren't inherently "risk-free"), it's just that the U.S. federal government is perceived to have the best credit-rating in the world, in terms of likelihood to pay back money loaned to it.

Still I think it can be useful to be reminded of obvious things.

Eliezer, if you anticipate a default more than 90 days in advance, it doesn't matter that other investors do also. You hold the Treasury bills to maturity and they are paid off before the default.

Hopefully Anonymous,

That is according to US based bond raters. A lot of people think there is politics in that. Do you really think the US government is more reliable about paying back its bonds than the Japanese one? Really?

Barkley Rosser,

I haven't studied the issue, but I suspect that the "objective" determination is that the US Govt. is less likely to default on bonds than the Japanese govt. Really. Japan had regime change as recently as the 1940s. And as a country, it probably faces greater threats than does the United States, particularly from China and North Korea. However, Tbills and Japanese govt. bonds are most likely in an elite class, in terms being seen as relatively low risk places to invest money.

Anyway, risk of default aside, what of interest-rate risk? Isn't Taleb's advice faulty because of that?

Taleeb's advice is extremely faulty, at least for long run investing. The black swan event that makes a more fully diversified debt/equity portfolio fail disastrously in the long term (20+ years) has a fairly high likelihood of taking out a short-term US treasury portfolio as well.

More importantly, while it may fare slightly better on average in the event of a complete meltdown in riskier financial markets -- short of that, it will almost always do quite a bit worse. If the chances of that meltdown are, say, 10%, we have to weigh insurance value in that scenario (which as Eliezer mentions is hardly perfect) against being many times as well off the other 90% of the time.

Stuart Armstrong,

I think you are way overstating things. Did you read earlier comments? Are you aware how close we came to defaulting in the 1990s when Congress and the president gridlocked over a budget? We have a systemic setup in contrast with all those countries with parliamentary systems that could let it happen much more easily with nothing near some kind of horrendous catastrophe. And if we began to experience some kind of serious pressure from a foreign creditor, China anyone? on top of some internal deep conflict and economic problems (and US politics is not all polarized, now is it?), it could happen.

Regarding this business of the foreign creditors, there is an important reason why most Americans simply pay no attention to our mounting foreign indebtedness: up until now the that humongoug foreign net indebtedness has not resulted in a noticeable net deficit on the investment income part of the current account part of the US international balance of payments. However, as that foreign net indebtedness increases, this will inevitably change. When we start to see several hundred billions of dollars flowing on net overseas as interest on that debt, and the accompanying upward pressure on US interest rates start to negatively impact the US economy, there might even be an outright move to do what Argentina did to our bankers, and what New York state did to British bankers back in the nineteenth century regarding the debts for financing the Erie Canal construction: consciously default.

The bottom line on why we even fuss about the "risk-free rate" is that it is a necessary input to the standard formuli for pricing all kinds of options and derivatives via Black=Scholes and its variations. Something has to go in there, even if the wise really do understand that the underlying asset on which that rate is based is not really so risk free after all.

It's not much of a singularity if there aren't real economic gains. I see no reason that prices of tdoay's typical consumption goods should go up. In fact, most of them should drop precipitously. Pricing of positional goods will skyrocket and become unaffordable to those who didn't create enough value or capture enough rents during the transition. It's hard to say what will become of economics in a time of no scarcity, though. I think most "needs" will become essentially free and the economy will consist primarily of positional goods.

One could argue on this definition that we are already pretty close to such an outcome, at least in the rich world.

I think you are way overstating things. Did you read earlier comments? Are you aware how close we came to defaulting in the 1990s when Congress and the president gridlocked over a budget?

I know, and I read those. However, all the 20th century defaults I actually know about - Argentina, the mentioned examples of the Ottoman and Austro-Hungarian empire, many countries after a revolution - were accompanied by civil disorder. Does anyone have recent examples of a peaceful government default? (there are a few examples I've found in the 19th century, though they were generally partial or temporary defaults).

As for the US, I think it's easy to exaggerate, in hindsight, the closeness to a default. I very much doubt that a proper default - a sustained refusal to honour debts - would have come out of that.

I think you'll find Ottoman and Austro-Hungarian finances were pretty shaky. Turkey was known as the "sick man of Europe" for a reason. U.S. T-bills would have been almost as good as the Bank of England :-) I'd point out that the UK defaulted (for some values of defaulted) in 1931-2 and stopped payments in forex on some war debts.

Mexico defaulted (kindasorta) in the 90s without having any more violence than Mexican politics tends to involve. Russia defaulted on the GKO bonds in 1998, without any more violence than post-Soviet politics tends to involve.

Stuart,

Argentina recently defaulted and all but got away with it. Yes, there were demonstrations in the streets, but there are also on a regular basis in the US. What is your definition of "civil disorder" then? Elections were held, there was no revolution or coup.

In fact, the Argentine example might yet come to mind in the next decade if not-so friendly foreign creditors start to give the US a hard time. I think it was Keynes who argued that if you owe somebody a million dollars you have a problem, but if you owe him a trillion dollars, he has a problem (have changed the numbers to account for inflation). We could default and view it as "screw them" act.

Yes, there were demonstrations in the streets, but there are also on a regular basis in the US. What is your definition of "civil disorder" then? Elections were held, there was no revolution or coup.

My argentinian friends living there described scenes of intense chaos and mass lawlessness - but that might be just a selection bias.

Mexico defaulted (kindasorta) in the 90s without having any more violence than Mexican politics tends to involve. Russia defaulted on the GKO bonds in 1998, without any more violence than post-Soviet politics tends to involve.

I'm convinced! You can have defaults without disasters. I'll buy some gold and international stocks and bonds to go along with my guns and petrol :-)

We could default and view it as "screw them" act.

Actually, seeing the anemic response from creditors to the Argentina default, contrasted with the howls of "moral hazard" that accompagnied it, it's strange that countries don't default more often. Maybe a default is an admission of failure, so leaders don't want to do it - even if it would be best for their country. Or maybe international diplomacy is restraining them.

There is no such thing as risk free, but expected rate with the lowest possible variance can be found.

For simplicity, I like real global GDP growth as a measure of how one performs compared to all agregated invesment.

I'm with Stuart Armstrong: how do you hedge against a US government default? "End of the world" may be an exaggeration, but what investment is going to be in good shape if the US decides not to pay back the national debt? Everything takes a big hit. The risk is non-zero, but it practically unavoidable.

Or maybe there are investments completely insulated from that collapse. I can't claim global expertise.

Zubon, I think that was much more true in 1950 (when I think the us. was 50% of the world economy) than it is to day, post-Cold War, when the US might be under 20% of the world economy, and where appreciation of market economics and liberal government are widely appreciated. Thankfully world economic product has heavily diversified away from the United State. With regions like the EU and East Asia, I think even a particularly disastrous US collapse wouldn't take the rest of the world down with it.

I just wanted to point out the fact that foreign governments have defaulted on debt does not prove this point. With a US treasury security you are promised to be paid a certain amount of US dollars at a certain time. With the exception of certain inflation protected securities, no promises are made regarding inflation. The US government controls the ability to tax and PRINT dollars so I think the odds are next to 0 that the politicians would default on these debts when they could just print away their problem. The term risk-free asset refers to the default risk, of course there is still interest rate risk, inflation risk, reinvestment risk and others. In this context I feel that the term risk-free is for all intents and purposes accurate.

May I submit reading anything by William Bernstein to anyone interested in a math-heavy discussion of this? The book "the intelligent asset allocator" is the most math heavy of the set.

His best quote on this is "assume a very fat tail" i.e. assume statistically unlikely events are rather likely as a group.

I would also like to take a moment to praise Alexander Hamilton and his friends for setting the precedent that the US has never defaulted. We were awfully close after the revolutionary war.

Perhaps he says more in Black Swan - but I don't see the quoted text as describing anything as risk free.

Treasury bills - as safe a class of instruments as you can manage to find on this planet

Is pretty much true. Its the single safest instrument that bears interest. Now I would not follow the rest of his advice, for reasons you mention I think it would be safer to hold some other notes as well some precious metals (which aren't interest bearing but at least float with inflation).

The other factor here that you don't touch on is that a lot of people believe that a US Treasury default would be pretty much the end of our currency and economy; notes issued by Swiss banks couldn't be expected to hold up since everyone indebted to them has some exposure to US assets or to someone else who does. I don't know if this is true but I'm quite sure many people believe it.