Assumption One
No market power. No individual buyer or seller, nor any group of buyers or sellers, has the power to affect the market-wide level of prices, wages, or profits.
Assumption Two
No economies of scale. Small plants can produce as cheaply as large ones.
Assumption Three
Perfect information about the present. Buyers and sellers know everything there is to know about the goods being exchanged. Also, each is aware of the wishes of every other potential buyer and seller in the market.
Assumption Four
Perfect information about the future. Contracts between buyers and sellers cover every possible future eventuality.
Assumption Five
You only get what you pay for. Nobody can impose a cost on somebody else, nor obtain a benefit from them, without paying.
Assumption Six
Price is a proxy for pleasure. The price of a given commodity will represent the quality and desirability and or utility derived from the consumption of the commodity.
Assumption Seven
Self-interest only. In economic matters, each person cares only about his or her own level of well-being.
Assumption Eight
No joint production. Each production process has only one product.