Justin,
Good question. I’m just now learning this stuff for myself, but I think the following is accurate:
SHORT ANSWER: It’s not that the boom causes an INCREASE in the capital stock so much as it’s that the boom causes the COMPOSITION of the capital stock to be different than otherwise, and thus inappropriate. When the proverbial “punch bowl” is taken away, a certain percentage of the demand for the output of the inappropriate capital structure disappears as a result.
LONG ANSWER:
The answer to your question turns on the fact of RESOURCE SCARCITY. Were resources unlimited, society would clearly choose to consume as much as possible as soon as possible, and therefore every increase in “productive capacity” would be of benefit. But because resources are of course limited, society must ration its consumption. This requires that society be selective, in any given time period, as to which goods it will consume, in which quantities, and in which order. In turn, this selection and ordering of consumption requires a specific pattern of production.
In this light, everything boils down to society’s time preference, as expressed in the rate of interest, between present consumption and future consumption (i.e. between consumption and investment) for any given level of resources at its command during a specified period of time.
The higher the magnitude of consumption which is deferred to the future, the lower is society’s “time preference”, the lower the rate of interest, and the “longer” becomes the structure of production. This means that productive capacity will be allocated to producing higher order capital goods (i.e. goods which are further removed, in both degree and time, from producing consumer goods). Were, instead, society’s time preference higher and thus weighted less toward deferred consumption and more toward present consumption, more productive capacity would be allocated to producing capital goods of a less-high order.
In this manner, society’s decision as to when to consume its scarce resources manifests itself in a specific pattern (i.e. this “specific pattern” being what Austrians call the “structure of production”) in the stock of capital. That is to say, society’s specific consumption decision manifests itself in a specific composition of the capital stock*.
The Fed monetary stimulus distorts the rate of interest, the price of capital, and thus distorts the preferred pattern of investment. The resulting capital structure no longer reflects society’s decision as to WHEN TO CONSUME its limited resources. Once the stimulus is removed, society’s decision as to when to consume will once again come to bear, and find expression in a MARKED LACK OF DEMAND for the output of the now-distorted capital structure.
*EDIT: I don’t know yet how, precisely, society’s time preference manifests itself in a specific production pattern. Why, for instance, a longer period of consumption deferment MUST result in more resource allocation to high-order capital goods. Thus, an explanation of the causes and effects in this regard is left out of the above analysis. However, it suffices to say that for the above analysis to hold, differing time preferences must NECESSARILY manifest themselves in differing structures of production.
EDIT 2: Also, I’ve unintentionally left out of the above analysis a consideration of the starting point for the time periods being discussed: Namely, does the analysis assume a starting point of an economy at full employment, or an economy at less than full employment?
EDIT 3: This is Hayek’s rather ambiguous assessment (from The Austrian Theory of the Trade Cycle, http://mises.org/tradcycl/avoidinf.asp#[1] ):
“There is of course, no doubt that temporarily the production of capital goods can be increased by what is called “forced saving”–that is, credit expansion can be used to direct a greater part of the current services of resources to the production of capital goods. At the end of such a period the physical quantity of capital goods existing will be greater than it would otherwise have been. Some of this may be a lasting gain: people may get houses in return for what they were not allowed to consume. But I am not so sure that such a forced growth of the stock of industrial equipment always makes a country richer, that is, that the value of its capital stock will afterwards be greater–or by its assistance all-round productivity be increased more than would otherwise have been the case. If investment was guided by the expectation of a higher rate of continued investment (or a lower rate of interest, or a higher rate of real wages, which all come to the same thing) in the future than in fact will exist, this higher rate of investment may have done less to enhance overall productivity than a lower rate of investment would have done if it had taken more appropriate forms.”
Of course, we would do well to proceed for now according to Hayek’s conclusion. Prior to discovering this, however, I had thought that the Austrians argument - here in apparent contradistinction to Hayek’s position - was in part that the capital structure during monetary inflation becomes highly disfigured and, therefore ultimately, much less productive.
Something clearly is still missing from this picture.
EDIT 4: But then here’s Roger Garrison, in The Austrian Theory of the Trade Cycle (http://mises.org/pdf/austtrad.pdf):
“According to Tullock’s [incorrect] understanding of the Austrian theory, the boom is a period during which the flow of consumer goods is sacrificed so that the capital stock can be enlarged. At the end of the boom, then, the capital stock would actually be larger, and the subsequent flow of consumer goods would be correspondingly greater. Therefore, the period identified by the Austrians as a depression would, instead, be a period marked by increased employment (labor is complementary to capital) and a higher standard of living. The [inadequate] stock-flow construction that underlies this line of reasoning does not allow for the structural unemployment that characterizes the crisis-much less for the complications in the form of the secondary depression.” pp. 16-17
This stands in seeming contrast to Hayek immediately above.