Reality+: Virtual Worlds and the Problems of Philosophy

by David J. Chalmers

Ursula Le Guin’s classic 1969 novel The Left Hand of Darkness describes a possible world where humans on the planet Gethen have no fixed gender. As Le Guin puts it in her 1976 article “Is Gender Necessary?”: “I eliminated gender to find out what would be left.” In an introduction to the novel, she writes: If you like you can read [this book], and a lot of other science fiction, as a thought-experiment. Let’s say (says Mary Shelley) that a young doctor creates a human being in his laboratory; let’s say (says Philip K. Dick) that the Allies lost the Second World War; let’s say this or that is such and so, and see what happens. . . . In a story so conceived, the moral complexity proper to the modern novel need not be sacrificed, nor is there any built-in dead end; thought and intuition can move freely within bounds set only by the terms of the experiment, which may be very large indeed. Thought experiments yield many insights. Le Guin’s thought experiment gives us insight into a possibility: It tells us something about gender as it could be. Robert Nozick’s thought experiment about the experience machine gives us insight into value: It helps clarify what is valuable to us and what isn’t. Zhuangzi’s butterfly dream gives us insight into knowledge: What can we know, and what can’t we know?