Business Economics · Main economic schools and their key features

Marxian Economics: Key Features and Surplus Value Explained

Updated 11 October 2026 · Fact-checked

Marxian economics is the school built on Karl Marx's critique of capitalism. It says labour creates value, and capitalists keep part of it as surplus value. This drives class conflict, capital accumulation and recurring crises. To answer exam questions, define the idea, explain the mechanism, then compare it with classical views.

Understand Marxian Economics

Marxian economics starts from a simple question: where does profit come from? Marx built on classical economists such as Smith and Ricardo, who said the value of a good is linked to the labour needed to make it. Marx kept that idea but used it to criticise capitalism rather than defend it.

The labour theory of value says the value of a commodity depends on the socially necessary labour time needed to produce it, at average skill and normal productivity. It is not the hours one slow worker happens to take. Marx separated use value (usefulness) from exchange value (what it trades for).

Under capitalism, workers do not own the means of production. They sell their labour power for a wage. The wage roughly covers what is needed to keep the worker alive and working. But the worker can produce more value than that wage in a day. The extra is surplus value, and the capitalist keeps it as profit. Marx called this exploitation, meaning a structural feature of the system, not a claim about any one cruel employer.

Marx described two main classes: the bourgeoisie (owners of capital) and the proletariat (wage workers). Their interests conflict over wages, hours and the share of output. Competition forces capitalists to reinvest surplus value and to replace labour with machinery. Marx argued this accumulation has built-in problems. He predicted a falling rate of profit, concentration of capital in fewer firms, a reserve army of unemployed that holds wages down, and recurring crises from overproduction or weak demand. He expected these tensions to end in a socialist system.

For the exam, treat this as a school of thought. You are asked what it says, how it differs from other schools, and what criticisms exist. Critics point out that the labour theory of value cannot easily explain prices, that the predicted collapse did not occur in the form Marx described, and that wages and living standards rose in many economies.

Key rules to remember

Marx's value of a commodity: Value = c + v + s; c = constant capital (machinery, materials used up), v = variable capital (wages), s = surplus value.
Rate of surplus value (rate of exploitation): s' = s ÷ v; Surplus value divided by variable capital. Also equals surplus labour time ÷ necessary labour time.
Organic composition of capital: OCC = c ÷ v; Ratio of constant to variable capital. Marx argued it tends to rise as firms mechanise.
Rate of profit: r = s ÷ (c + v); Profit relative to total capital advanced. If OCC rises while s' stays the same, r falls.

How to solve Marxian Economics questions

Use this method for both short-answer and written questions on Marxian economics.

1Read the command word. 'Explain', 'describe', 'compare' and 'evaluate' need different depth.
2Define the key term in one sentence, for example surplus value as value produced by labour beyond the value of labour power.
3Explain the mechanism in order: labour creates value, wages are less than value created, owners keep the surplus, competition forces reinvestment.
4Link to class conflict and to the predicted outcomes: falling profit rate, concentration of capital, reserve army of labour, crises.
5If the question asks for comparison, set Marx against classical economics point by point: who gets the surplus, harmony or conflict, view of capitalism's future.
6For numeric parts, write c, v and s clearly and apply s' = s ÷ v and r = s ÷ (c + v).
7Close with one or two criticisms or a limitation, and state a short conclusion.

Quickest way: Four-box recall: Value, Surplus, Class, Crisis

When to use it: Use it for MCQs and for planning a written answer in the first minute.

Value: labour time is the source of value.
Surplus: wages are less than the value workers create; the gap is surplus value.
Class: owners and workers have opposing interests.
Crisis: accumulation leads to a falling profit rate, concentration and recurring crises.
For numbers, compute s' = s ÷ v first, then r = s ÷ (c + v).

Common mistakes in Marxian Economics

Saying surplus value is the same as profit in the accounting sense.
Both relate to income left after costs, so they look alike.
Fix: Surplus value is a Marxian concept based on labour. Profit is the money form that surplus value takes, after it is shared with rent and interest.
Using total capital instead of wages as the base for the rate of surplus value.
Students mix up s' and the rate of profit.
Fix: s' = s ÷ v. The rate of profit is s ÷ (c + v). Check which one the question asks for.
Claiming classical economists saw no conflict and Marx saw only conflict.
Over-simplified summaries.
Fix: Ricardo recognised conflict between landlords, workers and capitalists over income shares. The key difference is that Marx treated exploitation and crisis as built into capitalism.
Treating the labour theory of value as saying any hour of work creates value.
The word 'labour' is read literally.
Fix: Say socially necessary labour time at average skill and productivity.
Presenting Marx's predictions as proven facts.
The theory is written in confident language.
Fix: Describe them as Marx's predictions and add that critics dispute them, for example because real wages rose in many countries.

Worked examples

Example 1

In a factory, a day's production uses constant capital of ₹60,000 and variable capital of ₹20,000. Surplus value created is ₹20,000. Calculate (a) the rate of surplus value, (b) the rate of profit, and (c) the value of output in Marx's terms.

Show the solution

Identify c = ₹60,000, v = ₹20,000, s = ₹20,000.
(a) s' = s ÷ v = 20,000 ÷ 20,000 = 1, or 100%.
(b) r = s ÷ (c + v) = 20,000 ÷ 80,000 = 0.25, or 25%.
(c) Value = c + v + s = 60,000 + 20,000 + 20,000 = ₹1,00,000.

Answer: Rate of surplus value 100%; rate of profit 25%; value of output ₹1,00,000.

Example 2

Explain why Marx predicted a falling rate of profit, using a numeric illustration. Keep s' at 100%. Compare a firm with c = ₹40,000 and v = ₹20,000 with one where c = ₹100,000 and v = ₹20,000.

Show the solution

Marx argued competition pushes firms to mechanise, so c rises relative to v. This raises the organic composition of capital.
Since only labour creates surplus value, s depends on v. With s' = 100% and v = ₹20,000, s = ₹20,000 in both cases.
First firm: r = 20,000 ÷ (40,000 + 20,000) = 20,000 ÷ 60,000 = 33.3%.
Second firm: r = 20,000 ÷ (1,00,000 + 20,000) = 20,000 ÷ 1,20,000 = 16.7%.
So with the same exploitation rate, a higher c ÷ v lowers the rate of profit.
Limitation: if s' rises enough as firms mechanise, the fall can be offset. Marx called this a tendency, not a certainty.

Answer: The rate of profit falls from about 33.3% to about 16.7% when c ÷ v rises from 2 to 5 with s' constant. This illustrates Marx's falling-rate-of-profit tendency.

Exam tips

Learn the four formulas and practise one numeric question; MCQs often test s' versus r.
For compare questions, write in pairs: Marx versus classical on value, surplus, conflict and the future of capitalism.
Always include at least one criticism in a written answer to earn evaluation marks.
Use the exact terms: socially necessary labour time, labour power, constant and variable capital.
Place Marx in the sequence of schools: classical, then Marx, then neoclassical and Keynesian.

Practice questions from Main economic schools and their key features

Marxian Economics: frequently asked questions

What is surplus value in Marxist economics?

Surplus value is the value workers create beyond the value of their labour power, which is roughly their wage. The capitalist keeps it. Marx saw it as the source of profit and the basis of exploitation.

What is the difference between classical and Marxian economics?

Both use a labour-based idea of value. Classical economists generally saw capitalism as a lasting, growth-producing system. Marx saw exploitation and class conflict as built into it, and expected crises and eventual transformation.

Is Marxian economics still relevant for the IAI exam?

It appears in the economic schools chapter, so you should know its key features and criticisms. Your syllabus weight for that chapter is small, so learn the core points well and do not over-invest time.

What is the labour theory of value?

It says a commodity's value comes from the socially necessary labour time needed to produce it. It is not based on the hours an individual takes. Marx used it to explain exploitation.