My past self had preferences about what the future looks like, and by refusing to respect them I can defect.
It seems to me your past self is long gone and doesn’t care anymore. Except insofar as your past self feels a sense of identity with your future self. Which is exactly my point.
Your past self can easily cause physical or financial harm to your future self. But the reverse isn’t true. Your future self can harm your past self only if one postulates that your past self actually feels a sense of identity with your future self.
I currently want my brother to be cared for if he does not have a job two years from now. If two years from now he has no job despite appropriate effort and I do not support him financially while he’s looking, I will be causing harm to my past (currently current) self. Not physical harm, not financial harm, but harm in the sense of causing a world to exist that is lower in [my past self’s] preference ordering than a different world I could have caused to exist.
My sister-in-the-future can cause a similar harm to current me if she does not support my brother financially, but I do not feel a sense of identity with my future sister.
I think I see your point, but let me ask you this: Do you think that today in 2010 it’s possible to harm Isaac Newton? What would you do right now to harm Isaac Newton and how exactly would that harm manifest itself?
Very probably. I don’t know what I’d do because I don’t know what his preferences were. Although… a quick Google search reveals this quote:
To me there has never been a higher source of earthly honor or distinction than that connected with advances in science.
I find it likely, then, that he preferred us not to obstruct advances in science in 2010 than for us to obstruct advances in science in 2010. I don’t know how much more, maybe it’s attenuated a lot compared to the strength of lots of his other preferences.
The harm would manifest itself as a higher measure of 2010 worlds in which science is obstructed, which is something (I think) Newton opposed.
(Or, if you like, my time-travel-causing e.g. 1700 to be the sort of world which deterministically produces more science-obstructed-2010s than the 1700 I could have caused.)
A little bit of both, I suppose. One needs to define “harm” in a way which is true to the spirit of the prisoner’s dilemma. The underlying question is whether one can set up a prisoner’s dilemma between a past version of the self and a future version of the self.
It seems to me your past self is long gone and doesn’t care anymore. Except insofar as your past self feels a sense of identity with your future self. Which is exactly my point.
Your past self can easily cause physical or financial harm to your future self. But the reverse isn’t true. Your future self can harm your past self only if one postulates that your past self actually feels a sense of identity with your future self.
I currently want my brother to be cared for if he does not have a job two years from now. If two years from now he has no job despite appropriate effort and I do not support him financially while he’s looking, I will be causing harm to my past (currently current) self. Not physical harm, not financial harm, but harm in the sense of causing a world to exist that is lower in [my past self’s] preference ordering than a different world I could have caused to exist.
My sister-in-the-future can cause a similar harm to current me if she does not support my brother financially, but I do not feel a sense of identity with my future sister.
I think I see your point, but let me ask you this: Do you think that today in 2010 it’s possible to harm Isaac Newton? What would you do right now to harm Isaac Newton and how exactly would that harm manifest itself?
Very probably. I don’t know what I’d do because I don’t know what his preferences were. Although… a quick Google search reveals this quote:
I find it likely, then, that he preferred us not to obstruct advances in science in 2010 than for us to obstruct advances in science in 2010. I don’t know how much more, maybe it’s attenuated a lot compared to the strength of lots of his other preferences.
The harm would manifest itself as a higher measure of 2010 worlds in which science is obstructed, which is something (I think) Newton opposed.
(Or, if you like, my time-travel-causing e.g. 1700 to be the sort of world which deterministically produces more science-obstructed-2010s than the 1700 I could have caused.)
Ok, so you are saying that one can harm Isaac Newton today by going out and obstructing the advance of science?
Yep. I’ll bite that bullet until shown a good reason I should not.
I suppose that’s the nub of the disagreement. I don’t believe it’s possible to do anything in 2010 to harm Isaac Newton.
Is this a disagreement about metaphysics, or about how best to define the word ‘harm’?
A little bit of both, I suppose. One needs to define “harm” in a way which is true to the spirit of the prisoner’s dilemma. The underlying question is whether one can set up a prisoner’s dilemma between a past version of the self and a future version of the self.