Economists, politicians, and others have been puzzled by business cycles since at least the early 19th century. One of the more unusual explanations was proposed by English economist William Stanley Jevons in the 19th century. He believed the ups and downs of an economy were caused by sunspot cycles, which affected agriculture and caused cycles of bad and good harvests. This hypothesis is not taken seriously today. Most business cycle theories fall into one of two categories.
Some economists assert that economies have basic flaws which, for some reason, lead to cycles.
Other economists insist that only some form of outside interference can cause swings from high to low unemployment. Unemployment and business failures are the most visible and characteristic signs of a recession .Those who accept the flawed economy theory usually insist that economies are far too large and complex to operate without a significant degree of government guidance and regulation. Those who hold the opposite view believe that economies are not inherently flawed and that there will be no business cycles as long as there is no outside interference from governments, banks, or other sources. All economies undergo stress and shock from time to time. Natural disasters, such as hurricanes, tornadoes, floods, and earthquakes, can do serious economic damage, but the damage tends to be localized.