I've been reading Cicero's De Officiis and in the last book he discusses the relationship between morality and expedience. I don't mean to go into the subject in depth here, but at one point Cicero gives examples of business deals to see whether they are fraudulent. I'd like to propose a similar one here and see what you think.

Say you visit a yard sale or are browsing a website like Ebay and find a great deal. In fact, the person selling this thing must be really generous or simply ignorant of its value. Should one offer the seller a price more equivalent to the product's value, or is it okay to buy something at a "steal" when the seller may not know what he has?

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DAVIDIVS DOCTVS VTRIVSQVE LINGVAE
Husband of Emilia
Member: First Reformed Presbyterian Church of Durham (RPCNA) - Durham, NC
Currently in the process of transferring membership to an as-yet-undecided church in Chapel Hill
Student: University of North Carolina at Chapel Hill, German Literature and Classics