Sounds like what you really want is an introductory macroeconomics textbook that will give you an explanation of the standard models mainstream economists use.<p>But your example - why business cycles occur - is really more of a debate than a generally understood phenomenon. That&#x27;s part of the reason <i>why</i> they occur.
(part of the explanation is straightforward: people are less likely to borrow if they think that problems in the economy might make repayment difficult, and optimism&#x2F;pessimism about the future tends to be shared by large proportions of the population. But the dynamics aren&#x27;t universally agreed upon.)