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> 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 th

> 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.
    - mannykannot 7y ago
      I am assuming that, in your statement of my position, where you wrote "figuring out what it looks like" you meant "figuring out what it looks like elsewhere." I also want to make it clear that I take "based on" to mean that the deduced remote measurements are a necessary part of the argument. Nevertheless, it is still not quite there: as it stands, even after these adjustments, it leads to the conclusion that Swebs' argument is circular, yet we are both agreed that it is not. This goes back to the part of Swebs' argument that says, in effect, "if we were to observe the expansion of the universe from a distant galaxy, it would look like it does from here" (specifically, that we are at the center in both cases.) My position is that I do not think one could make any successful argument of that form - i.e. which depends on comparing what one would measure at a remote location with what one observes here - without it being circular. My reason for thinking that is so is that I suspect that, if the argument is valid (Swebs' was not), you cannot deduce what those remote measurements are without begging the question. Now we get to the critical part: my reason for thinking it would be begging the question is that, if the measurements are capable of resolving the UEIS/UEOS issue, then I think they must have a causal dependency on which way UEIS/UEOS goes, and thus, on account of that dependency, one could not deduce what would be measured remotely without first picking one or the other. Update: Let's look at it from the other direction: if your deduced remote measurements do not differ depending on whether you assume UEIS or UEOS, then how are they going to resolve the issue? This is what makes Swebs' argument an invalid one. Note that this does not rule out UEIS/UEOS being settled by local measurements, and in fact, early in this thread, I mentioned what I thought might be a possible candidate: directly determine the Hubble constant without reference to redshift, through measurements over time of objects whose distance can be measured by other means. Such methods would not depend on comparing local and deduced remote measurements, and would render moot the whole issue of whether we can deduce relevant remote measurements, as well as all arguments that rely on doing so. So my position is that I do not think there are any arguments that are both valid and non-circular, that depend on comparing deduced remote measurements to local ones, that show we already have observations that resolve the issue, and I will stand by it until I am persuaded otherwise. One valid counter-example would be sufficient.

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.
  - mannykannot 7y ago
    I am assuming that, in your statement of my position, where you wrote "figuring out what it looks like" you meant "figuring out what it looks like elsewhere." I also want to make it clear that I take "based on" to mean that the deduced remote measurements are a necessary part of the argument. Nevertheless, it is still not quite there: as it stands, even after these adjustments, it leads to the conclusion that Swebs' argument is circular, yet we are both agreed that it is not. This goes back to the part of Swebs' argument that says, in effect, "if we were to observe the expansion of the universe from a distant galaxy, it would look like it does from here" (specifically, that we are at the center in both cases.) My position is that I do not think one could make any successful argument of that form - i.e. which depends on comparing what one would measure at a remote location with what one observes here - without it being circular. My reason for thinking that is so is that I suspect that, if the argument is valid (Swebs' was not), you cannot deduce what those remote measurements are without begging the question. Now we get to the critical part: my reason for thinking it would be begging the question is that, if the measurements are capable of resolving the UEIS/UEOS issue, then I think they must have a causal dependency on which way UEIS/UEOS goes, and thus, on account of that dependency, one could not deduce what would be measured remotely without first picking one or the other. Update: Let's look at it from the other direction: if your deduced remote measurements do not differ depending on whether you assume UEIS or UEOS, then how are they going to resolve the issue? This is what makes Swebs' argument an invalid one. Note that this does not rule out UEIS/UEOS being settled by local measurements, and in fact, early in this thread, I mentioned what I thought might be a possible candidate: directly determine the Hubble constant without reference to redshift, through measurements over time of objects whose distance can be measured by other means. Such methods would not depend on comparing local and deduced remote measurements, and would render moot the whole issue of whether we can deduce relevant remote measurements, as well as all arguments that rely on doing so. So my position is that I do not think there are any arguments that are both valid and non-circular, that depend on comparing deduced remote measurements to local ones, that show we already have observations that resolve the issue, and I will stand by it until I am persuaded otherwise. One valid counter-example would be sufficient.