"Free lunch?"

There is no such thing as  free lunch.” This statement is one of the most famous in modern economics. Is it correct? Economics is a science, and so you can challenge the claim with evidence. Did you have a “free lunch” last week? Does that lunch qualify as evidence that refutes the claim? Maybe economist mean some thing a little different by the term than the ordinary person might. Let’s look at a situation in which a free lunch might not be really free. 

Suppose Putra wants to borrow Gretha’s car and takes Gretha out for a free lunch. This lunch is not really free for Gretha, for she must either return the favor by lending her car or go through the pain of saying no to Putra. Here we have the idea of an exchange- 0ne lunch exchanged or traded for one Saturday night’s worth of car use. Economists study exchanges, especially exchanges for money, such as lunches for money and car rentals for money. There are also exchanges not involving money: I call exchange of one good for another good without the use of money. In a modern economy most exchanges involve money—for example, one Tempe for Rp 7000. Primitive economies rely on barter—for one stone ax.

“ Barter is the exchange of one good for another without the use of money”

But is there no such thing as a free lunch? Is there no case on record where someone has eaten a free lunch with no expectation of a return favor or anything else? Of course. We have all had a free lunch with no return favor expected. But “no free lunch” is a little “in” joke for economist.