Who was right? Was the end of the classical gold standard a disaster? Or were the old orthodox economists just a bunch of no-fun fuddy-duddies, who didn't get it at all? And if so, how did they metamorphose from fuddy-duddies into nutball cranks?
First, it's easy for us to dismiss the inflationists on logical grounds. Inflationism simply cannot be right. It violates logic. Nothing can violate logic.
Second, an orthodox economist need not be a goldbug. The difference between paper and gold, as monetary goods, is immaterial. People hold money to defer consumption into the future, not for the industrial qualities of the money itself. Gold makes a good monetary system not because gold is "intrinsically" valuable in some sense, but because the supply is strictly limited. Ideally, there would be no new gold mining at all. And we can duplicate this effect with paper money, by issuing a certain number of notes and double-promising not to issue any more. (The advantage of gold is that the promise is a lot more credible.)
Rather, the difference is between a hard or inelastic currency, and a soft or "elastic" one. The former cannot be inflated; the latter can. An ideal hard currency has no new supply.
The key fact about money is that what matters to you is not how much money you have, but what fraction of the total money supply you have. It is the latter than determines your power to exchange money for other goods, in competition with present moneyholders. Eg: if, following Hume's Archangel Gabriel, we turn every dollar into two dollars (being careful to adjust debts as well), we have changed nothing.
Even simple inflation - printing money and spending it, Keynesian style - can be emulated with an ideal hard currency. To "print" new money in this currency, simply confiscate it pro rata from all present holders of the currency. Eg, if you want to print 1/100th the present money supply, find every dollar in the world, pay its owner 99 cents, and use the leftover pennies to fund your plan.
The effect of this policy is precisely the same as that of inflating an elastic currency, although the elastic implementation is much more straightforward. Perhaps this is the advantage of elasticity. But it avoids the critical question, which is why we'd want to do this in the first place. Oddly enough, although we know they are semantically identical, the inflation option seems much more fair and reasonable. Oddly, too, even Adams seems to acknowledge that, although an elastic currency may be pernicious, it is desired by many.
Keynes and Fisher did not propose inflation as an all-purpose stimulant for general fun. They proposed it as a cure for economic recessions and depressions, which were certainly in no short supply at the time. We are entering a recession or depression now, so it seems wise to revisit the issue. Is cocaine a good remedy for depression? Why do so many people want to inflate?
Again, the answer is easy. What we see in a recession or depression is a drop in consumer spending. Since spending is the flip side of production, we can think of the GDP (the sum of the prices of all goods and services sold by businesses to consumers) for any country as the amount of money spent on that country's goods and services. If that number falls by, say, 5%, the average business in the country has produced 5% too many goods and services.
Obviously, this is quite painful. And it also gives rise to calls for inflation - or, to use a more precise term, monetary dilution. There is an easy way to correct the situation to our business's satisfaction: print 5% more money, and spend it on goods and services. Hence the "stimulus."
If we switch back to hard-currency mode and look at what we're doing, it is even weirder. In order to prop up consumer demand, we steal one nickel from every holder of a dollar, add it all up, and spend it on goods which we throw away. Is this healthy? Keynes thought it was.
Basically, the way to perceive the "new economics" is in exactly the same way that Adams perceived it: not a sane government policy, but a response to pressure groups. Fortunately or unfortunately, those pressures were a lot stronger after WWI than before it, and sound money went the way of the dodo. So, for example, our pressure group here is the business owner. Farmers in debt also tend to do quite well with inflation. But, again: any monetary debasement can be modeled as a monetary transfer.
As in the case of AGW, we ended up with "new economics" because that was what Washington wanted to hear. The case is the same today: Barack Obama's "stimulus" proposal involves doubling Federal discretionary spending, ie everyone's budget. Obviously, this makes quite a few people very happy. And it probably spreads the loot around a little better than if we were just to give it all, up front, to Tony Rezko.
Hence the death of orthodox economics. The orthodox economists of the 19th century, the believers in sound money, were not in general policymakers. They viewed their task as one of describing the economy, not controlling it. But in the '20s and '30s, when university men started to move into government, politically palatable solutions were needed. The Austrians and other orthodox historians had nothing of the sort. So they were left out of the pie when all the power got distributed, and today they have no government jobs and only a few marginal academic ones.
What at least the Austrians had, however, was an accurate understanding of the disease that the Keynesians and Fisherites were trying to treat - the pattern of repeated booms and busts. The "new economists" called it the "business cycle," a term implying some endogenous origin in the commercial community - which, coincidentally or not, tended to align with Harding and Coolidge rather than Hoover and FDR. Bankers and economists tend to be more left-wing.