Agreements must be kept; without this presumption no exchange beyond immediate barter is possible.
From Roman law, and the foundation of contract and treaty alike. Without the presumption, no exchange beyond simultaneous barter is possible, which is why enforcement institutions precede complex markets.
In practice
- A builder takes a deposit in January and starts work in March, and neither party rechecks in between whether the other still means it.
- A market where deals are routinely reopened reverts to simultaneous exchange, which is why escrow, deposits and enforcement precede complex trade.
- Further reading
- Wikipedia
- Subject
- Law & Politics
- Essay
- Rules that restrain power, and advice on using it