If humanity goes extinct this century, that drastically reduces the likelihood that there are humans in our solar system 1000 years from now. So at least in some cases, looking at the effects 1000+ years in the future is pretty straightforward (conditional on the effects over the coming decades).
In order to act for the benefit of the far future (1000+ years away), you don’t need to be able to track the far future effects of every possible action. You just need to find at least one course of action whose far future effects are sufficiently predictable to guide you (and good in expectation).
The initial claim is that for any action, we can assess its normative status by looking at its long-run effects. This is a much stronger claim than yours.
If humanity goes extinct this century, that drastically reduces the likelihood that there are humans in our solar system 1000 years from now. So at least in some cases, looking at the effects 1000+ years in the future is pretty straightforward (conditional on the effects over the coming decades).
In order to act for the benefit of the far future (1000+ years away), you don’t need to be able to track the far future effects of every possible action. You just need to find at least one course of action whose far future effects are sufficiently predictable to guide you (and good in expectation).
The initial claim is that for any action, we can assess its normative status by looking at its long-run effects. This is a much stronger claim than yours.