If you come across lemons, make lemonade! The third principle of effectual reasoning is at the heart of entrepreneurial expertise—the ability to turn the unexpected into the profitable. Expert entrepreneurs learn not only to work with surprises but also to take advantage of them. In most contingency plans, surprises are bad—the worst-case scenarios. But because entrepreneurs do not tie their idea to any theorized or preconceived “market,” anything and everything is potentially a surprise that can lead to a valuable opportunity.