> Econ 101 time: value is subjective. Human beings merely use value as a description - it does not exist inside of any object or inside of any equation
Econ 201 time: value is concrete, the definition of value is subjective. I can say that the value of two exchanged objects are concrete - that they have the same embedded value.
No,that's econ negative 1. People don't exchange things because they are of equal value, they exchange things because each feels himself better off after the trade.
and that's certainly happening. money now is better than money later (time value of money, net present value discounting), during economic downturns people don't start buying the dip like there's no tomorrow, even though it's very likely that they would make bank in 5-10 years. (because people are risk averse)
similarly we are bad at managing spread out risks (climate change, road traffic incidents)
That's a simplifying assumption used to make the accounting practical.
But knowing that someone bought something on Amazon doesn't tell you how much the buyer would have paid or how low the seller would have been willing to go. (There are gains from trade and who gets them depends on negotiations and the competitive situation.) Also, one or even both of them may have made a mistake. People return things they purchased all the time, and they may regret purchases they don't return.
We are fortunate that for many kinds of goods, we usually don't have to pay the full value of what we buy, due to competition.
Econ 201 time: value is concrete, the definition of value is subjective. I can say that the value of two exchanged objects are concrete - that they have the same embedded value.