That is a dangerous oversimplification of the law of contracts. The doctrine of consideration is very old. Commonwealth courts have made many, many exceptions t

That is a dangerous oversimplification of the law of contracts. The doctrine of consideration is very old. Commonwealth courts have made many, many exceptions to that doctrine. It is a okay way of conceptualizing contracts, but it isn't 'good law' and shouldn't be relied on. (I'm providing legal information, not legal advice; hire a lawyer and please don't rely on legal advice you get from comment sections; if you truly want to avoid lawyers and do it yourself, I would suggest reading E.A. Farnsworth's "Contracts")