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Some could claim that happiness is utterly irrelevant to what is going on in the world. What is necessary and sufficient for happiness is what is happening in our heads, namely, our mental states. Hedonism is one of these mental states theories, according to which we can obtain happiness when pleasure outweighs pain; what is needed for happiness can be reduced to pleasure and pain that are nothing but mental states.

Hedonism faces a strong objection from the “experience machine” thought experiment by Robert Nozick. Imagine a machine that directly affects your neural circuits so that you would entertain very pleasurable experiences. They are not real, however, in the sense that actually they do not have correspondent events in the world. Would you use this machine for the rest of your life, at the expense of the real experiences? According to Nozick, many would prefer the real life, even though it was much harder than the virtual ones.

Anti-mental theorists seem to hold both that:
(1) One must strongly believe that their mental states must correspond to the reality.
(2) This belief C must be true.

Using an experience machine would not satisfy (2). The first part of this presentation examined this condition (2), and concluded that under some situation in which we cannot know in principle whether we live in the real world or a virtual world, everyone could agree that we can obtain happiness in a virtual world. The second part of the presentation explored a possible application, whose tentative conclusion was that an artificial conscious life with good states is presumably preferable to death, if the subject cannot get the knowledge that their conscious life is artificially manipulated.

(Yoshiyuki Hayashi)