Why doing a PhD is often a waste of time

The Economist:

ON THE evening before All Saints’ Day in 1517, Martin Luther nailed 95 theses to the door of a church in Wittenberg. In those days a thesis was simply a position one wanted to argue. Luther, an Augustinian friar, asserted that Christians could not buy their way to heaven. Today a doctoral thesis is both an idea and an account of a period of original research. Writing one is the aim of the hundreds of thousands of students who embark on a doctorate of philosophy (PhD) every year.
In most countries a PhD is a basic requirement for a career in academia. It is an introduction to the world of independent research–a kind of intellectual masterpiece, created by an apprentice in close collaboration with a supervisor. The requirements to complete one vary enormously between countries, universities and even subjects. Some students will first have to spend two years working on a master’s degree or diploma. Some will receive a stipend; others will pay their own way. Some PhDs involve only research, some require classes and examinations and some require the student to teach undergraduates. A thesis can be dozens of pages in mathematics, or many hundreds in history. As a result, newly minted PhDs can be as young as their early 20s or world-weary forty-somethings.