Exogenous technological change is technology growth that the model treats as coming from outside the economy. In Intermediate Macroeconomic Theory, it shifts productivity upward and drives long-run growth in the Solow model.
Exogenous technological change is technological progress that the macro model treats as coming from outside the economy itself. In Intermediate Macroeconomic Theory, that means the model does not try to explain why the innovation happened. It just takes the improvement as given and asks how it changes output, capital per worker, and long-run growth.
In the Solow Growth Model, exogenous technological change is usually written as a rise in the efficiency of labor or as a shift in the production function. If workers become more productive because of a better machine, software, or production process, then the economy can produce more output with the same amount of capital and labor. That is why growth from technology is different from growth from simply adding more machines or more workers.
The word exogenous matters because it tells you the cause is outside the model. A textbook might assume the technology growth rate is constant, which makes the math cleaner and gives the model a steady long-run path. Under that setup, the economy can keep growing in output per worker even after capital deepening runs into diminishing returns.
This is one reason the Solow model separates growth into pieces. Capital accumulation can raise output for a while, but it does not generate endless growth by itself. Exogenous technological change is what keeps living standards rising over time in the model. Without it, output per worker would eventually level off once the economy reached its steady state.
A good way to picture it is a factory that keeps the same number of workers and machines but gets better blueprints, better software, or better engineering methods. The factory produces more because the technology behind the process improved, not because the managers changed savings behavior inside the model. That is the core idea: the model treats the tech improvement as an outside force, then tracks its effect on productivity and growth.
This term is one of the main reasons the Solow model can explain sustained growth in living standards. If you only had capital accumulation, diminishing returns would eventually slow growth down. Exogenous technological change gives the model a way to keep output per worker rising over the long run.
It also helps you separate short-run movements from long-run growth. A jump in investment can raise capital per worker, but a technology shift raises the whole production frontier, so the economy can produce more at every level of input. That distinction shows up when you compare two countries with similar savings rates but different productivity levels.
In class, this concept also sets up the contrast with endogenous growth theory. If a professor asks why technology growth is treated as external in Solow, you are usually being pushed to notice what the model leaves unexplained. That gap is what later theories try to fill with research and development, human capital, and innovation incentives.
You will also use this term when reading graphs or steady-state diagrams. A rise in technology changes the effective amount of labor, shifts the balanced growth path, and changes how you interpret output per worker over time. If you can track that shift, you can explain why economies may grow even when savings, depreciation, and population growth stay the same.
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view galleryTechnical Progress
Technical progress is the broader growth idea behind exogenous technological change. In the Solow model, technical progress is usually the force that raises productivity over time, while exogenous tells you the model treats that progress as given rather than explained. If a problem asks why output per worker keeps rising in the long run, technical progress is the mechanism you point to.
Total Factor Productivity (TFP)
TFP is the measured productivity level that captures output not explained by measured capital and labor inputs. Exogenous technological change often shows up as a rise in TFP, because better methods let the same inputs produce more output. When you see TFP in a graph or data set, think of it as the empirical side of the model's technology term.
Solow Residual
The Solow residual is the part of output growth left over after accounting for capital and labor growth. Economists often interpret it as technological change or productivity growth. That makes it a practical way to think about exogenous technological change when you are working with data, since the model itself does not fully explain where the technology gain came from.
Endogenous Growth Theory
Endogenous growth theory pushes back against the Solow assumption that technology comes from outside the model. Instead, it tries to explain innovation through investment in research, education, and ideas. This comparison is useful when a question asks you to identify what Solow leaves out and how later models try to make technology growth part of the economic system.
A problem set or short-answer question will usually ask you to show what happens to output per worker when technology improves. The move is to say that exogenous technological change shifts the production function upward, raises productivity, and supports long-run growth even after capital reaches diminishing returns. If you get a Solow graph, look for a change in the effective labor term or a higher balanced growth path. In a written response, you should connect the technology shock to higher steady-state output per worker, not just to more output in one period. If the question compares models, use it to explain why Solow treats innovation as outside the model while endogenous growth theory tries to explain it from within.
These are easy to mix up because both deal with long-run growth. Exogenous technological change treats innovation as coming from outside the model, while endogenous growth theory explains technological progress using economic decisions like R&D and human capital investment. If the question asks where growth comes from, Solow says outside the model, but endogenous theories say inside the model.
Exogenous technological change is technology growth that the model treats as coming from outside the economy.
In the Solow Growth Model, it raises productivity and shifts the production function upward.
Capital accumulation alone faces diminishing returns, so technology is what keeps output per worker growing in the long run.
The term matters because it separates growth caused by more inputs from growth caused by better ways of producing.
If you see TFP or the Solow residual, you are often looking at the data side of exogenous technological change.
It is technological progress that the model treats as coming from outside the economy. In the Solow framework, it raises productivity and shifts output upward without being explained by savings, labor supply, or capital accumulation inside the model.
It lets the economy keep growing in output per worker over time. Without it, capital accumulation hits diminishing returns and growth slows, but with technology growth, the steady-state path itself keeps moving upward.
Not exactly, but they are closely related. Exogenous technological change is the theory idea, while TFP is often the measured productivity term that captures its effect in the data. In many macro problems, a rise in TFP is how the model shows tech progress.
Ask whether the model explains where innovation comes from. If technology is assumed to arrive from outside the model, that is exogenous technological change. If the model explains innovation through R&D, ideas, or human capital decisions, that is endogenous growth theory.