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Figure 1: Wage Curves for a Fluke Case |
1.0 Introduction
This post revisits Harrod-neutral technical change, in the context of
the choice of technique.
I used Matlab code to
obtain the results in this post.
2.0 Technology
The technology (Table 1) in this example
is a modification and
extension of a reswitching example from Bruno, Burmeister, & Sheshinski (1966). Each column specifies the physical
inputs (labor-hours, tons, bushels) needed to produce a specified output at a specified point in time.
Each process uses up its inputs and exhibits constant returns to scale
(CRS). Technical change results
in the reduction of labor coefficients. The labor coefficients for the first processes in the two
industries decrease at the same rate, while the labor coefficients in the other two processes also
decrease at the same rate, but possibly differing from the rate of decrease in the first processes.
Table 1: A Technology
| Iron Industry | Corn Industry |
Process a | Process b | Process c | Process d |
Labor | e1 - θt | (2/5) e1 - φt | (33/50) e1 - θt | (1/100) e1 - φt |
Iron | a1,1,a = 0 | a1,1,b = 1/3 | a1,2,c = 1/50 | a1,2,d = 71/100 |
Corn | a2,1,a = 1/10 | a2,1,b = 1/20 | a2,2,c = 3/10 | a2,2,d = 0 |
OUTPUTS | 1 ton iron | 1 ton iron | 1 bushel corn | 1 bushel corn |
A technique consists of a process for producing corn and a process for producing iron. Four
techniques (Table 2) exist in this economy. Iron and corn are basic commodities, in the sense of
Sraffa, in all techniques. Alpha and Delta experience Harrod-neutral technical change, possibly at
different rates. Beta and Gamma combine processes from the two techniques with neutral technical
change. How does the analysis of the choice of technique, with prices of production, vary as
technical change occurs in secular time?
Table 3: Specification of Techniques
Technique | Iron Industry | Corn Inudstry |
Alpha | Process a | Process c |
Beta | Process a | Process d |
Gamma | Process b | Process c |
Delta | Process b | Process d |
3.0 Prices of Production and the Choice of Technique
Prices of production must be such that managers of capitalist firms are willing to continue
producing iron and corn.
In calculating prices of production, I abstract from secular change in labor coefficients.
A price system is associated with each technique. I assume labor is advanced, and wages
are paid out of the surplus at the end of the year. A bushel corn is the numeraire.
For each technique, the wage and the price of iron can each be expressed as a function
of the rate of profits.
Figure 1 plots the wage curves for the four techniques, at a given time and with
given rates of technical change. The technique with the highest wage is cost-minimizing at a given
rate of profits. The outer envelope is the wage frontier. It is composed out of the wage curves for
the Delta, Alpha, and Beta techniques. The wage curve for Gamma is on the frontier only at the
first switch point, at approximately 45.8 percent. This is a fluke switch point. Around this switch
point, a higher wage or lower rate of profits results in processes in both industries changing in the
cost-minimizing case. Only one industry has two processes in cost-minimizing techniques in a
non-fluke switch point.
The other switch point, at approximately 167.1 percent, is not a fluke and illustrates capital-
reversing. The Beta technique requires less labor, through the economy as a whole, to produce a
net output of a bushel corn than the Alpha technique does.
Around the switch point, a higher wage is associated with firms wanting to employ
more labor per bushel corn produced net in the economy.
4.0 Partitions of the Parameter Space by Fluke Switch Points
A switch point at which four wage curves intersect is only one of four fluke switch points that
arise in the example, depending on the rates of technical progress and the time. Figure 2 shows a
partitioning of the parameter space, based on these fluke switch points. Each of the partitions is an
affine function with a slope of unity. This property of the partitioning of the parameter space, that
all partitions are straight parallel lines with unit slope, is a consequence of considering techniques
with processes drawn from two techniques undergoing Harrod-neutral technical change.
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Figure 2: A Partition of the Parameter Space |
The analysis of the choice of technique is qualitatively invariant in each numbered region.
Table 3 lists the cost-minimizing techniques, in order of an increasing rate of profits, in each
region. Only techniques on the frontier are listed. Capital-theoretic ‘paradoxes’ that arise in each
region are noted. Only the switch point in region 5 corresponds to obsolete marginalist intuition.
A lower wage or higher rate of profits, around the switch point, is associated with a more labor-
intensive and less capital-intensive technique.
Table 3: Specification of Techniques
Region | Techniques | Properties |
1 | Delta, Gamma, Alpha, Beta | Capital-reversing, reverse substitution of labor for Alpha vs. Beta switch point. |
2 | Delta, Beta, Alpha, Beta | Reswitching, capital-reversing, and the reverse substitution of labor.
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3 | Beta, Alpha, Beta | Reswitching, capital-reversing, and the reverse substitution of labor. |
4 | Alpha, Beta | The reverse substitution of labor. |
5 | Alpha, Beta | 'Non-perverse' switch point. |
5.0 A Trajectory through the Parameter Space
The dashed line in Figure 2 represents a possible trajectory through the parameter space, with
fixed rates of technical progress for the production processes. Figures 3 and 4 graph the maximum
wage and the wage at switch points, as functions of time, along this trajectory. At the intersection
of the trajectory with the partition for the fluke switch at which at which four wage curves intersect
the wage curve for the Beta technique replaces the wage curve for the Gamma technique on the
frontier. The wage curve for the Delta technique no longer appears on the frontier at a nonnegative
rate of profits after the trajectory passes the partition for the switch point between Beta and Delta
on the wage axis. Similarly, when the trajectory crosses the next partition, the first switch point
between Alpha and Beta is no longer on the frontier at a nonnegative rate of profits.
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Figure 3: A Trajectory Through the Parameter Space |
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Figure 4: A Trajectory Through the Parameter Space (Cont'd) |
When this switch point between Alpha and Beta exists at a rate of profits of -100 percent,
ac,0,2 = ac,0,2.
In other words, around the other switch point, at a positive, feasible rate of profits, a
higher wage leaves unchanged how much labor is hired per unit of gross output in the corn
industry. Before the trajectory crosses the partition for this fluke switch point, the labor coefficient
in the last process is less than the labor coefficient in the penultimate process. A higher wage
around the illustrated switch point is associated with more employment in the corn industry per
unit of gross output. This is the reverse substitution of labor.
Harrod-neutral technical progress cannot change the ranking of techniques by the maximum
rate of profits. In this example, one of the mixed techniques, Beta, is cost-minimizing at the
maximum rate of profits. At the start, Delta is cost-minimizing at a rate of profits of zero, and the
example exhibits capital-theoretic ‘paradoxes’. If the rate of neutral technical progress in Alpha
exceeds the rate of neutral technical progress in Delta, Alpha must eventually be cost-minimizing
at a rate of profits of zero. The trajectory in the example illustrates how capital-theoretical
‘paradoxes’ can disappear.
6. Conclusions
Harrod-neutral technical progress yields particularly simple structures in the parameter space.
All partitions corresponding to fluke switch points are parallel affine functions with slopes of unity,
and the rates of profits at which fluke switch points occur do not vary with neutral technical
progress. The fluke at which four wage
curves intersect illustrates this property. No double fluke cases, at the intersections of partitions can
arise here. Likewise, no fluke switch points can appear on the axis for the rate of profits.
I previously claimed that technology
that supports multiple switch points between two techniques can only be a temporary phenomenon, as one technique
supplants another with technical progress.
The results of the numerical experimentation in this post are in tension with that claim.
In some trajectories, neutral technical change eliminates
the capital-theoretic ‘paradoxes’ of reswitching and capital-reversing.
In other trajectories, it does not.
I created the example to start with reswitching. If neutral technical progress in Delta
exceeds that in Alpha, the reswitching example persists through secular time.
In practice, technical change will vary in its rate and have biases. For example, Marx-biased
technical change is a mix of capital-using and labor-saving technical change (Foley, Michl,
& Tavani 2019). Technical change will often involve more than processes from two existing
techniques. It frequently includes the creation of new industries and new commodities. The
analysis of Harrod-neutral technical change, entangled with the choice of technique, provides a
baseline to contrast with structures in parameter spaces found in other analyses.