PRINCETON, New Jersey — In a popular Internet role-playing game called Second Life, people can create a virtual identity for themselves, choosing such things as their age, sex and appearance. These virtual characters then do things that people in the real world do, such as having sex.

Depending on your preferences, you can have sex with someone who is older or younger than you — perhaps much older or younger. In fact, if your virtual character is an adult, you can have sex with a virtual character who is a child. If you did that in the real world, most of us would agree that you did something seriously wrong. But is it seriously wrong to have virtual sex with a virtual child?

Some Second Life players say it is, and have vowed to expose those who do it. Meanwhile, the manufacturers, Linden Labs, have said they will modify the game to prevent virtual children from having sex. German prosecutors have also become involved, although their concern appears to be the use of the game to spread child pornography, rather than whether people have virtual sex with virtual children.