In a market economy there is no central planning authority to dictate what goods get produced, how much should be made or who gets what in the end. The production, distribution and consumption of scarce goods and services is determined on the market through the interactions of many buyers and sellers all acting in their own self-interest. Therein lies the fundamental insight in this weeks readings: This complex market system that emerges through these interactions is a product of our collective actions, but not necessarily of our design.
According to Roberts the idea of relating the natural emergence of complex systems to social phenomena like the development of human language or markets dates back to Scottish Enlightenment-era thinkers like Adam Ferguson and Adam Smith and were later elaborated on by F.A. Hayek's writings on "spontaneous order". Although some scholars, namely Murray Rothbard, have noted that this idea pre-dates the Scottish Enlightenment in the writings of Chinese philosopher Zhuangzi who first noted that "Good order results spontaneously when things are let alone".
Regardless of its origins this concept of spontaneous order has also been influential in other fields like evolutionary biology. Richard Dawkins first coined the term "designoid" to describe a complex object or system that looks like the product of intelligent and deliberate design but is actually the result of an unguided natural process, i.e. evolution by natural selection. In this sense free markets can also be thought of as a designoid system.
As a designoid system the market, like evolution, is driven by natural forces. Natural selection is the key mechanism behind evolution, like supply and demand are the key mechanisms behind the market. There's no need for an intelligent designer behind biological phenomenon like natural selection, just as there's no need for a central planner behind economic phenomenon like mutually beneficial exchange.
While it's true that we don't always have to like the way in which these natural forces compel us, for someone to blame the free market because gas, food, health-care or any other commodity is priced higher than what they would prefer seems as futile as blaming natural selection for endowing them with a superfluous vestigial organ.