I'd be interested in an attempt to take these simple ideas: credit, debt, etc and created a simple model that shows how credit leads to cycles, where I can play with parameters and see exactly what affacts what.
For example, why cycles? Why should credit across multiple people synchronize into cycles? why not just average out? Exactly what assumptions go into this?
But your example - why business cycles occur - is really more of a debate than a generally understood phenomenon. That's part of the reason why 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/pessimism about the future tends to be shared by large proportions of the population. But the dynamics aren't universally agreed upon.)