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I had written a long response to your various points, but this seems to get to the crux of the matter: > It's circular if we assume the form of the expansion..

I had written a long response to your various points, but this seems to get to the crux of the matter: > It's circular if we assume the form of the expansion... Yes. > ...If the real form influences our measurements, and we use that to figure out what telescopes would show... In what way is that not exactly the sort of circularity that we just agreed about above, given that the real form is the issue to be decided?

Dylan16807 7y ago
> In what way is that not exactly the sort of circularity that we just agreed about above, given that the real form is the issue to be decided? Because measurements are not assumptions. If we use assumptions about UEOS/UEIS to figure out what telescopes show, and use that as evidence for UEOS/UEIS, that's a circular argument. If we use measurements to figure out what telescopes show, without any assumptions about UEOS/UEIS, and then use that as evidence for UEOS/UEIS, that's not a circular argument. (And obviously there are always some assumptions when being sufficiently pedantic. It's an assumption that the sun still exists, etc. That's why I'm specifically saying "assumptions about UEOS/UEIS".)
- mannykannot 7y ago
  > If we use assumptions about UEOS/UEIS to figure out what telescopes show, and use that as evidence for UEOS/UEIS, that's a circular argument. Exactly, and that is what my comment to Swebs was intended to forestall (I have already made this point, several posts back.) That comment, being a reply to Swebs, must be read in that context (obviously, as you had not even joined the thread yet), and in that post, Swebs was making an argument that UEOS/UEIS has already been settled by observation. In other words, the resolution of UEOS/UEIS was, in fact, the conclusion that Swebs was claiming to have observational proof of. Using a pre-existing resolution of UEOS/UEIS to deduce what observations might be made elsewhere simply didn't enter into the discussion, as in that case, the issue being debated would have already been resolved. > Because measurements are not assumptions. I don't have measurements, Swebs didn't have measurements (though he thought he did), and it has become clear that you don't have measurements either. Maybe someone does, but they have not yet shown up in this discussion.
  - Dylan16807 7y ago
    > in that post, Swebs was making an argument that UEOS/UEIS has already been settled by observation. At most that was just being wrong, not having a circular argument. > In other words, the resolution of UEOS/UEIS was, in fact, the conclusion that Swebs was claiming to have observational proof of. Yes, Swebs was making a conclusion about UEOS/UEIS. But both the circular and non-circular arguments do that. Swebs was not using assumptions about UEOS/UEIS to reach that conclusion. > I don't have measurements, Swebs didn't have measurements (though he thought he did), and it has become clear that you don't have measurements either. Maybe someone does, but they have not yet shown up in this discussion. That doesn't matter. If I say "A implies B", and I have no evidence for A, then I have not proven B. But it is not a circular argument. You can have an argument that is both valid and unproven. The argument "Measurements will/might/do tell us UEOS/UEIS" is not circular.
    - mannykannot 7y ago
      >> in that post, Swebs was making an argument that UEOS/UEIS has already been settled by observation. > At most that was just being wrong, not having a circular argument. I did not call Swebs' argument circular. I will repeat, for at least the third time now, that my comment about circularity was intended to forestall the use of a circular argument, of the sort that you have acknowledged is possible, in attempts to correct it. >> I don't have measurements, Swebs didn't have measurements (though he thought he did), and it has become clear that you don't have measurements either. Maybe someone does, but they have not yet shown up in this discussion. > That doesn't matter... It is not intended to be an argument for the circularity of anything, it is simply a reply to your comment about measurements, pointing out the lack of them in this discussion.
      - Dylan16807 7y ago
        > I did not call Swebs' argument circular. I know. Swebs has not proposed a full argument. We're talking about hypothetical arguments that swebs, or someone else, could propose. Right? > I will repeat, for at least the third time now, that my comment about circularity was intended to forestall the use of a circular argument, of the sort that you have acknowledged is possible, in attempts to correct it. Here are the things you said: "Of course, we can figure out what it would look like, but if that is your argument, then it is circular." "you have to make assumptions about the latter in order to deduce the former" "I do not think that there is any set of deduced remote measurements that a) show, as a certainty, that space itself is expanding, and b) can be deduced without implicitly or explicitly assuming a position on the issue." "What I said was that there are certain claims that, if they were made, would result in a circular argument. I did not say that Swebs had made those claims, as he had not done so; I wrote it in an attempt to forestall a trip down a dead end (so much for that!)" So, correct me if this summary is wrong, "Any argument based on figuring out what it looks like has to be a circular argument." Do you stand by that statement, or am I misinterpreting something? Because that's what I disagree with. I think it's possible to make an argument, based on figuring out what it looks like, that is not circular. This argument would use measurements as the basis for its figuring/deducing. > circular argument, of the sort that you have acknowledged is possible It's always possible to make a circular argument. What matters is whether it's possible to make a non-circular argument.

Dylan16807 7y ago

> In what way is that not exactly the sort of circularity that we just agreed about above, given that the real form is the issue to be decided? Because measurements are not assumptions. If we use assumptions about UEOS/UEIS to figure out what telescopes show, and use that as evidence for UEOS/UEIS, that's a circular argument. If we use measurements to figure out what telescopes show, without any assumptions about UEOS/UEIS, and then use that as evidence for UEOS/UEIS, that's not a circular argument. (And obviously there are always some assumptions when being sufficiently pedantic. It's an assumption that the sun still exists, etc. That's why I'm specifically saying "assumptions about UEOS/UEIS".)

mannykannot 7y ago
> If we use assumptions about UEOS/UEIS to figure out what telescopes show, and use that as evidence for UEOS/UEIS, that's a circular argument. Exactly, and that is what my comment to Swebs was intended to forestall (I have already made this point, several posts back.) That comment, being a reply to Swebs, must be read in that context (obviously, as you had not even joined the thread yet), and in that post, Swebs was making an argument that UEOS/UEIS has already been settled by observation. In other words, the resolution of UEOS/UEIS was, in fact, the conclusion that Swebs was claiming to have observational proof of. Using a pre-existing resolution of UEOS/UEIS to deduce what observations might be made elsewhere simply didn't enter into the discussion, as in that case, the issue being debated would have already been resolved. > Because measurements are not assumptions. I don't have measurements, Swebs didn't have measurements (though he thought he did), and it has become clear that you don't have measurements either. Maybe someone does, but they have not yet shown up in this discussion.
- Dylan16807 7y ago
  > in that post, Swebs was making an argument that UEOS/UEIS has already been settled by observation. At most that was just being wrong, not having a circular argument. > In other words, the resolution of UEOS/UEIS was, in fact, the conclusion that Swebs was claiming to have observational proof of. Yes, Swebs was making a conclusion about UEOS/UEIS. But both the circular and non-circular arguments do that. Swebs was not using assumptions about UEOS/UEIS to reach that conclusion. > I don't have measurements, Swebs didn't have measurements (though he thought he did), and it has become clear that you don't have measurements either. Maybe someone does, but they have not yet shown up in this discussion. That doesn't matter. If I say "A implies B", and I have no evidence for A, then I have not proven B. But it is not a circular argument. You can have an argument that is both valid and unproven. The argument "Measurements will/might/do tell us UEOS/UEIS" is not circular.
  - mannykannot 7y ago
    >> in that post, Swebs was making an argument that UEOS/UEIS has already been settled by observation. > At most that was just being wrong, not having a circular argument. I did not call Swebs' argument circular. I will repeat, for at least the third time now, that my comment about circularity was intended to forestall the use of a circular argument, of the sort that you have acknowledged is possible, in attempts to correct it. >> I don't have measurements, Swebs didn't have measurements (though he thought he did), and it has become clear that you don't have measurements either. Maybe someone does, but they have not yet shown up in this discussion. > That doesn't matter... It is not intended to be an argument for the circularity of anything, it is simply a reply to your comment about measurements, pointing out the lack of them in this discussion.
    - Dylan16807 7y ago
      > I did not call Swebs' argument circular. I know. Swebs has not proposed a full argument. We're talking about hypothetical arguments that swebs, or someone else, could propose. Right? > I will repeat, for at least the third time now, that my comment about circularity was intended to forestall the use of a circular argument, of the sort that you have acknowledged is possible, in attempts to correct it. Here are the things you said: "Of course, we can figure out what it would look like, but if that is your argument, then it is circular." "you have to make assumptions about the latter in order to deduce the former" "I do not think that there is any set of deduced remote measurements that a) show, as a certainty, that space itself is expanding, and b) can be deduced without implicitly or explicitly assuming a position on the issue." "What I said was that there are certain claims that, if they were made, would result in a circular argument. I did not say that Swebs had made those claims, as he had not done so; I wrote it in an attempt to forestall a trip down a dead end (so much for that!)" So, correct me if this summary is wrong, "Any argument based on figuring out what it looks like has to be a circular argument." Do you stand by that statement, or am I misinterpreting something? Because that's what I disagree with. I think it's possible to make an argument, based on figuring out what it looks like, that is not circular. This argument would use measurements as the basis for its figuring/deducing. > circular argument, of the sort that you have acknowledged is possible It's always possible to make a circular argument. What matters is whether it's possible to make a non-circular argument.