Peter Jones writes: > A computation is not a series of states. A computation is an > implementation > of an algorithm, and algorithms include conditional statements which > must be modelled by something with counterfactual behaviour -- > by something which *could have* execute the other branch.
Whatever else a computation is, it is a series of states. My computer is going through a series of physical states, with the earlier states determining the later states. If the earlier states were different, then the later states would also be different, hence the computer handles counterfactuals. However, this is so with any physical system: it goes through a series of states, the earlier states determine the later states following the laws of physics, and had the earlier states been different, so would the later states. Now, I suppose you would say that the states in a rock are random, while those in a computer are not. But what is to stop someone from designing a computer so that there is no pattern to its internal states unless you have the key? Suppose you find two inputless electronic devices, powered up, with complex and at first glance random currents circulating in their internal components. One of these devices is in fact implementing a computation, deliberately scrambled to keep it secret from prying eyes, while the other is just a decoy with random electrical activity. Without access to the key, would you be able to tell which is which? Another question: I can see why a computer should be able to handle counterfactuals if it is to be of practical use, but what is wrong with saying that a recording implements a computation, whether that is adding two numbers or having a conscious experience? Stathis Papaioannou _________________________________________________________________ Be one of the first to try Windows Live Mail. http://ideas.live.com/programpage.aspx?versionId=5d21c51a-b161-4314-9b0e-4911fb2b2e6d --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~----------~----~----~----~------~----~------~--~---
