Editing No such thing as a free lunch (section)

==== Economics ====
In economics, no free lunch demonstrates [[opportunity cost]]. [[N. Gregory Mankiw|Greg Mankiw]] described the concept as follows: "To get one thing that we like, we usually have to give up another thing that we like. Making decisions requires trading off one goal against another."<ref>''Principles of Economics'' (4th edition), p. 4.</ref> The idea that there is no free lunch at the societal level applies only when all resources are being used completely and appropriately – i.e., when [[economic efficiency]] prevails. If not, a 'free lunch' can be had through a more efficient utilization of resources. Or, as [[Fred Brooks]] put it, "You can only get something for nothing if you have previously gotten nothing for something."  If one individual or group gets something at no cost, somebody else ends up paying for it. If there appears to be no direct cost to any single individual, there is a [[social cost]].  Similarly, someone can benefit for "free" from an [[externality]] or from a [[Public good (economics)|public good]], but someone has to pay the cost of producing these benefits. (See [[Free rider problem]] and [[Tragedy of the commons]].)