In classical economics, the statement that supply creates its own demand is popularly known as the law of which economist?

Introduction / Context:
This conceptual question from economics asks about a famous proposition known as Say law. Recognising which economist is associated with the idea that supply creates its own demand is essential for understanding classical macroeconomic theory and its contrast with later Keynesian ideas.

Given Data / Assumptions:

• The key statement is that supply creates its own demand.
• The options list well known economists from different schools of thought.
• The question is about the law name, not about who criticised it.
• We assume the context of classical economic theory.

Concept / Approach:
Say law, named after French economist Jean Baptiste Say, asserts that the act of production generates income that is sufficient to purchase the output produced, so that general overproduction is unlikely in the long run. This idea underpinned classical belief in self adjusting markets. The approach is to recall that this law carries the name of J. B. Say, not of Adam Smith, Marshall or Keynes.

Step-by-Step Solution:
Step 1: Read the statement supply creates its own demand and recognise it as a well known slogan.Step 2: Recall that this phrase is commonly linked with Say law in macroeconomics.Step 3: Identify that Say refers to Jean Baptiste Say, usually written as J. B. Say in short form.Step 4: Look at the options and find the name J. B. Say.Step 5: Choose J. B. Say as the correct answer.

Verification / Alternative check:
Textbooks on macroeconomics and history of economic thought explicitly name this proposition as Say law. They attribute it to J. B. Say and describe how it implies that aggregate supply will generally equal aggregate demand. The same textbooks also discuss how Keynes later challenged this law, which further confirms the association with J. B. Say rather than with Keynes or other economists.

Why Other Options Are Wrong:
Alfred Marshall made major contributions to microeconomics and partial equilibrium analysis but is not credited with this particular law.
David Ricardo worked on theories of rent, comparative advantage and distribution, not on the principle that supply creates its own demand.
Adam Smith is regarded as the father of modern economics and wrote about the invisible hand, but Say law is not named after him.
John Maynard Keynes criticised the idea that supply automatically creates its own demand; he did not propose this law but argued that demand can be insufficient, leading to unemployment.

Common Pitfalls:
Some candidates see the word law and immediately think of well known names like Adam Smith or Keynes without recalling the specific phrase. Others mistakenly attribute the concept to Keynes because he discussed it extensively, but in fact he opposed it. Remembering the label Say law alongside the name J. B. Say is a simple way to answer correctly.

Final Answer:
The statement that supply creates its own demand is known as the law of J. B. Say.