Defoe never named a source. Alexander Selkirk's widely publicized 1709 rescue is the real-life account most often cited as the model, but historian Andrew Lambert and others argue this single-source reading is a false premise, since the novel differs from Selkirk's own story in concrete ways: Crusoe is shipwrecked rather than self-marooned, and his island is already inhabited rather than solitary.
What would resolve this A surviving Defoe letter, manuscript note, or contemporary account naming his source or sources directly; no such document is currently known.
OpenLiterary history and eighteenth-century book historyRobinson Crusoe (Wikipedia)