The Founder of Economics

How William Petty Invented Economics Before It Had a Name

There’s a long line of people who get credit for shaping economics as we know it—Adam Smith, Keynes, Friedman. But before any of them, there was William Petty, the 17th-century mastermind who built the foundations of economic thought before the field even had a name. If you trade, invest, or just keep an eye on the markets, you owe something to Petty, whether you realize it or not.

Who Was William Petty?

Petty was a polymath—a physician, statistician, economist, and even a surveyor for Cromwell. He wasn’t just a theorist sitting in a library; he was a man who got his hands dirty. He mapped Ireland, studied diseases, and then decided to figure out how money actually worked. If you want to talk about fundamental analysis, he was doing it in an era when most people were still relying on gut instincts.

Economics Before Economics

Before Petty, people thought about trade, prices, and taxation, but no one had really systematized it. He looked at the economy like an engineer, breaking it down into measurable parts. He coined the term “political arithmetic,” which is basically what we now call data-driven economic analysis. His idea was simple: instead of debating policies in the abstract, why not use numbers?

This was radical. At the time, policy decisions were based on power, tradition, and occasionally, divine right. Petty’s approach—quantifying wealth, labor, and productivity—was the beginning of what would become modern economic theory.

The First GDP?

One of Petty’s biggest contributions was his attempt to calculate the total wealth of England and Ireland. In doing so, he laid the groundwork for GDP—a stat we now take for granted but was groundbreaking at the time. He estimated the value of land, labor, and trade, trying to quantify the nation’s power in monetary terms.

His calculations weren’t perfect, but the logic behind them was. He understood that a nation’s wealth wasn’t just about how much gold it had (the prevailing view at the time) but about its productive capacity—its people, land, and commerce.

Labor Theory of Value & Trading Applications

If you’ve ever studied economics, you’ve probably heard about the labor theory of value. Most people associate it with Karl Marx, but Petty was toying with the idea centuries earlier. He tried to figure out what determined the price of goods, and his answer was simple: labor and land.

This is relevant for traders, too. If you’re evaluating companies, what’s your real metric for value? Book value, future earnings, or something more fundamental? Petty’s early work suggests that economic value comes down to productive output—something that applies whether you’re looking at a company, a country, or a commodity.

Petty’s Impact on Markets and Policy

The real test of any economic theory is whether it influences decisions, and Petty’s work certainly did. His statistical approach to taxation and national wealth influenced economic policy in England, and his emphasis on quantification eventually led to the data-driven models we use today.

If you trade macro trends, Petty’s fingerprints are everywhere. Government data releases, GDP growth forecasts, employment figures—these all trace back to his idea that economies should be measured, not just theorized.

Why It Matters Today

Markets today are awash with data, but the core idea—understanding economic fundamentals through numbers—is still the game. Traders using macro models, investors looking at fundamental value, or even analysts breaking down GDP components are all following a path Petty helped lay down.

Before Smith wrote The Wealth of Nations or Ricardo introduced comparative advantage, Petty was already thinking in terms of numbers, productivity, and economic power. He didn’t just theorize—he calculated.

So next time you look at a GDP report or assess a company’s real economic value, remember William Petty. He might not get the mainstream credit, but if anyone deserves to be called the father of economics, it’s him.