It is more appropriate to compare a healthy free economy to a complex ecosystem, than to a machine. A typical machine, like a car engine, can fail if you remove any single critical part. A healthy ecosystem contains no single part that is critical for its entire existence.

The other difference is that a machine, even a complex one, is by definition capable of being understood in total, otherwise one would not be able to build it in the first place. Also, most healthy ecosystems can heal even relatively massive disruptions, although its form and the species comprising it may change.

A metaorganism like an ecology or an economy cannot be analyzed as a whole, any more than one can predict with any accuracy exactly what the clouds will look like on a given day. Chaos, you know. Certainly many elements can be studied and understood. Biologists know how many of the interactions in an ecosystem work, and weathermen can make gross predictions with some accuracy, like whether or not there will be clouds on a given day.

I recommend a book, "Bionomics," by Michael Rothschild. Some excerpts from the Preface:

The market is not an invention of capitalism. It has existed for centuries. It is an invention of civilization. -Mikhail Gorbachev (June 8, 1990)

Capitalism, or the market economy, or the free-enterprise system—whatever you choose to label it—was not planned. Like life on earth, it did not need to be. Capitalism just happened, and it will keep on happening. Quite spontaneously. Capitalism flourishes whenever it is not suppressed, because it is a naturally occurring phenomenon. It is the way human society organizes itself for survival in a world of limited resources.

A capitalist economy can best be comprehended as a living ecosystem. Key phenomena observed in nature—competition, specialization, cooperation, exploitation, learning, growth, and several others—are also central to business life. Moreover, the evolution of the global ecosystem and the emergence of modern industrial society are studded with striking parallels.

...The most difficult concept to accept about the natural world is that it runs itself. No conscious force is needed to keep the ecosystem going. Life is a self-organizing phenomenon. From the interplay of hormones in the human body to the expansions and contractions of the great Arctic caribou herds, nature's intricately linked feedback loops automatically maintain a delicate, yet robust balance. Markets perform the same function in the economy. Without central planning, buyers and sellers constantly adjust to changing prices for commodities, capital, and labor. A flexible economic order emerges spontaneously from the chaos of free markets.

Needless to say, this thinking bears little resemblance to conventional economics. Two centuries of economic thought, both capitalist and socialist, are based on the concept of “economy as machine” rather than “economy as ecosystem.” Nonetheless, history has demonstrated that no economy behaves like a simple, cyclical machine. Like ecosystems, economies are spectacularly complex and endlessly adaptable.

Consequently, it is bionomics—which studies economic relations among organisms and their environments—that offers the best vantage point for a total rethinking of the received economic wisdom. Sprinkled throughout the book, wherever appropriate, the bionomic approach is distinguished from those of traditional capitalists and socialists. But the acid test for any economic view is not how it differs from its predecessors, but how it would work if applied in the “real world.”

As such, the closing chapters in parts II through VIII rely on the bionomic perspective to assess several of today's most pressing—and seemingly unrelated—economic questions: Why does America save and invest too little? How did Japan grab world economic leadership from the United States? Why did America lose the War on Poverty? Why does pollution get worse even as we spend more to stop it? Why are so many of America's public schools so awful? Why exactly did capitalism flourish while socialism collapsed? And, more important, given the underlying bionomic forces at work, which new policies can harness these forces and provide genuine solutions to these dilemmas?

For readers ideologically wedded to either end of the political spectrum, the answers to these questions will be, disconcerting. While certainly not “pro” socialist, the argument made here is not “pro” capitalist in any conventional way. It regards capitalism as the inevitable, natural state of human economic affairs. Being for or against a natural phenomenon is a waste of time and mental energy. Like it or not, the sun rises in the east. Meaningful economic issues always boil down to, given that capitalism exists, how can it be made better?

In short, this book calls for a profound change in our expectations of government, for a new understanding of how it can and cannot be used to foster prosperity. Bionomics does not deny the need for a social safety net, but it compels a rethinking of the net's design. The traditional notion of government's economic role—pushing the buttons and twisting the dials of society's economic machinery—is replaced by a vision of government as the astute cultivator of society's economic ecosystem, patiently nurturing the natural processes of growth.