Really? Because value and market price are separate things in marginalism.

Using the rational model somebody will only purchase something when it's price is below how much the person values the object.

It's related to consumer surplus. To make it measurable we use money as an approximate judge to work out much somebody values it. But the market price and how much somebody values something are different things in marginalism at the core.

It may depend on who you talk to, but Isee much equivocation between concets of price and value, in both micra ('wealth creation" / 'wealth creator") and macro (GDP) domains.

But yes, costs, price, and value are three distinct, though connected, concepts.

You have to understand most writing is aimed towards the layman, so they use market price as a proxy.

I hate the term wealth creator as well. But it certainly is possible to create to wealth. If you take things that people don't value that much, use them in a way to provide something that people do value. You have created wealth.

I'm curious what you mean by that, because it seems to me the exact opposite. Orthodox Economics 101 introduces consumer surplus precisely to separate price from value.

That would be a more correct view.

In much debate and discussion I see "market value" substituted for "value". Often the implication is a vague one, as withmuch equivocation. pg's argumentventures there.

Keep in mind that Smith, Ricardo, and Marx each commit this error, including in the Smith passage I quoted. So do the Marginalists, or at leaast most of them.

Mariana Mazzucato may be an exception. (I've just discovered her, still going through her work.)

https://www.ted.com/talks/mariana_mazzucato_what_is_economic...

Separating value and price is 101 of marginal economics.

There couldn't be consumer surplus without it. I don't know how you could be marginalist and believe market price = value for user.

In theory. In practice just about every quantitative method or metric used to measure social welfare or individual well being falls back on price. And since our culture has a fetish for positivism and anything that looks like “math” those are the fixed assumptions that guide our decision making.

The fundamental principle of marginalism is, er, marginalism: that the derivative of supply or demand functions is what determines market price (not to be confused with "value", though it often is). The marginal cost or value.