1. People have preferences - given a choice between goods, consumers can make a decision on which is preferred.
2. Preferences can and do differ across individuals - allows for trades to occur. (ex: Coke vs Pepsi)
3. More is preferred to less - all goods, not individual goods
4. People are willing to substitute one good for another - willing to make trade-offs
5. The more we have of a good, the less we value an additional unit of that good.