Suppose someone offers to sell some poor sod a supposedly productivity-enhancing perpetual motion machine ... Is it incorrect for me, as a third party, to say t

Suppose someone offers to sell some poor sod a supposedly productivity-enhancing perpetual motion machine ... Is it incorrect for me, as a third party, to say that this would be a foolish investment Since you say "perpetual motion machine", I assume that you're saying that the purchaser is being defrauded, since we know that there's no such thing as perpetual motion. But that's exactly the second point I was making in my first response. For a market to work, there needs to be some protection of the sanctity of a contract. When the buyer discovers that all he's got is snake oil, when he contracted for something real, he should be able to seek restitution. Without this, the market's not going to get off the ground.