Final answer:
Contracts that require both parties to perform duties and follow conduct rules for enforceability are conditional contracts. The legal system's enforcement of such contracts is vital for economic security and growth.
Step-by-step explanation:
When both parties to a contract must perform certain duties and follow rules of conduct to make the contract enforceable, the contract is conditional. A contract becomes conditional when it specifies that the obligations are contingent upon the occurrence of certain named conditions.
In contrast to aleatory contracts, which rely on chance events for fulfillment, or unilateral ones, wherein only one party has obligations, conditional contracts require both parties to fulfill conditions for the contract to be executable.
The security offered by a legal system, which enforces contracts, is essential for economic growth, as it reduces the risk of non-payment and thereby encourages individuals and firms to engage in transactions.