All of Rupert's Comments + Replies

Rupert52

I made the following observation to Chris on Facebook which he encouraged me to post here.

My point was basically just that, in reply to the statement "If we don't have such a model to reject, the statement will be tautological", it is in fact true relative to the standard semantics for first-order languages with equality that there is indeed no model-combined-with-an-interpretation-of-the-free-variables for which "x=x" comes out false. That is to say, relative to the standard semantics the formula is indeed a "logical truth" in that sense, although we usua... (read more)

0Chris_Leong
Indeed. If we want such a counter-model, then we'll need a different formalisation. This is what I provided above. I would be surprised if this were the case. I guess my argument above doesn't aim to argue for the Law of Identity a priori, but rather as a way of representing that our variables don't need to be more fine-grained given a particular context and a particular equivalence function. In other words, we adopt the Law of Identity because it is part of a formalisation (more properly, a class of formalisations) that is useful in an incredibly wide range of circumstances. At least part of why this is useful so widely because we can use it to formalise parts of our cognition and we use our cognition everywhere.
Rupert10

Point C is a particular combination of utilities. The particular combination of utilities is not attainable via re-distribution while the economy is in state a. If a change took place so that the economy was now in state c, then point C would be attainable by re-distribution.

(And there is a point common to both the curves a and c, but just from knowing that the utilities of Citizens 1 and 2 were at that particular point wouldn't allow you to know whether the economy is in state a or c, that would be extra information, and this extra information would be necessary in order to know which other points you could get to via re-distribution from your current situation.)

3JBlack
Ah good, I didn't misunderstand that then. I'm still confused as to why there are not 5 different Kaldor-Hicks improvement relations, one for each state of the economy, instead of just one. In the following passage in the post: B is a KHI over A in state b, but not in any other state. C is a KHI over B in state c, but not in any other state. As far as I can see, there in no economic state (and therefore no KHI relation) in which both B is a KHI over A and C is a KHI over B, and so the question of transitivity is irrelevant.
Rupert10

A Kaldor-Hicks improvement is a change of state of the economy from A to B such that B can be converted into a Pareto improvement by re-distribution, and such that A cannot be converted into a Pareto improvement of B by re-distribution. 

Every labelled point on that diagram permits re-distribution (because it lies on a curve).

1JBlack
They all permit re-distribution in different states of the economy though, so I'm not sure why they're even on the same diagram except to save the space of having a different diagram for each economic state. So for example, there is a curve labelled a, which corresponds to a particular economic state and points can be moved only along that curve in that state (per your earlier clarification). Point C is not on curve a, and so no redistribution is possible from there in economic state a.
Rupert10

Each curve corresponds to a "state of the economy". To get to a state where you could start re-distributing by moving along a different curve to the one you were originally moving along would require a change of state. When re-distributing, you can only move along one curve corresponding to the current state of the economy.

1JBlack
Oh, I see: Kaldor-Hicks improvement is a family of relations that depend upon the underlying economic state, not just a single relation. So in that diagram there are five states of the economy, and a separate Kaldor-Hicks relation for each one. In most of the economic states, only one of the points permits any redistribution at all. This seems ... kinda useless? Are you sure you're interpreting the diagram correctly?
Rupert10

Oh yes, and when the economy is in a given state you are only allowed to move along one curve. The curves are allowed to intersect, but you can't change which curve you are moving along when doing re-distribution. The explanation I just added of why the curves are allowed to intersect may help.

Rupert10

All of the curves represent states of the economy such that a re-distribution of resources will correspond to a movement along that curve. A change in state of the economy can be explained by a change in technological knowledge, a change in climate, the discovery of a deposit of a particular resource, stuff like that. "Re-allocation of resources" can correspond to re-allocation of quite a complex bundle of goods. The projections of the points on the co-ordinate axes merely represent the utilities of each of the two citizens, where only the order relations between utilities matters. 

1Rupert
Oh yes, and when the economy is in a given state you are only allowed to move along one curve. The curves are allowed to intersect, but you can't change which curve you are moving along when doing re-distribution. The explanation I just added of why the curves are allowed to intersect may help.
Rupert10

Let me be sure I understand what you're saying? If someone wants to argue on the internet that abortion should be prohibited by the criminal law, or that there isn't any moral obligation to be vegan, then I shouldn't moralize about the fact that I disagree with them? I mean, I can think of ways that you could maybe argue that point, I just want to make sure I understand you though.

Rupert50

My main thought would be that you consider the risk factors of physical intimacy but possibly ought to look a bit more closely at whether there are risk factors associated with avoiding physical intimacy (are you sure that that's not harmful as well if taken to sufficient lengths?) 

3Raphaëll
Interesting point. I do think there are risks in avoiding physical intimacy altogether, for vastly different reasons. Now, trying to navigate when it's harmful to have physical intimacy and when it's not is the hard part!
2remizidae
It would be an unusual partner who would agree to no physical intimacy (possibly including kissing and hugging) for two weeks so that OP can "reflect on the relationship." That sends a strong signal that you're about to get dumped. 
Rupert20

My main thought would be that you consider the risk factors of physical intimacy but possibly ought to look a bit more closely at whether there are risk factors associated with avoiding physical intimacy (are you sure that that's not harmful as well if taken to sufficient lengths?) 

2Mati_Roy
FYI, your comment was posted 3 times, probably because of a LessWrong bug that makes it seems as if your comment was posted when you click on 'submit'
Rupert100

My main thought would be that you consider the risk factors of physical intimacy but possibly ought to look a bit more closely at whether there are risk factors associated with avoiding physical intimacy (are you sure that that's not harmful as well if taken to sufficient lengths?) 

Rupert10

Thanks for the clarification. Possibly that reduces the interest of the observations about computational complexity.

Rupert*Ω110

However, because topology on is finer than topology on here, this still shows how the proof of the Lawvere fixed point theorem can be applied here to give Brouwer fixed point theorem as corollary, which could conceivably be a publishable result (see what "Geometry and Topology" think about that), and this could still be sorta kinda maybe relevant to Scott's original motivation for looking at the problem (if you're okay with working with two different topologies on the space of agents, one finer than the other... (read more)

RupertΩ110

Let be with generalised Cantor space topology, and be with product topology, a closed disc in a finite-dimensional Euclidean space. Then there is a continuous surjection . I don't know how to show that there is a topological space with carrier set and a continuous surjection . Thanks to Alex Mennen for pointing out the problem.

1Rupert
However, because topology on A′ is finer than topology on A′′ here, this still shows how the proof of the Lawvere fixed point theorem can be applied here to give Brouwer fixed point theorem as corollary, which could conceivably be a publishable result (see what "Geometry and Topology" think about that), and this could still be sorta kinda maybe relevant to Scott's original motivation for looking at the problem (if you're okay with working with two different topologies on the space of agents, one finer than the other). But this is a very big space of agents you're talking about here. Correction: need not only that topology on A′ is finer than topology on A′′, but also, given arbitrary open subset of X, take pre-image under evaluation map in XA′′×A′′, projection onto first factor and then pre-image of that under the continuous surjection A′→XA′′, it needs to be shown that this set is open in both topologies. I believe that this can indeed be done for an appropriate class of spaces X for the pair of topologies in question.
RupertΩ110

When I look at my post the LaTeX code isn't formatting properly; if anyone can let me know how to fix that.

2Ben Pace
I fixed it. In our editor, use cmd-4/ctrl-4 to do LaTex, not dollar signs. (The thing you did would work in the markdown editor – you can go into settings to change to that editor if you'd like.)
Rupert*Ω260

I have just now submitted an attempted solution to this problem to "Geometry and Topology". I claim that the space you are looking for is ( being the least uncountable cardinal) with the ``generalised Cantor space topology", that is for each countable well-ordered bit-string you have a basic open set consisting of all bit-strings of length with as an initial fragment. Since this topological space has quite a large cardinality I'm somewhat unclear whether this is helpful for your proposed application and ... (read more)

1Rupert
Let A′ be 2ω1 with generalised Cantor space topology, and A′′ be 2ω1 with product topology, X a closed disc in a finite-dimensional Euclidean space. Then there is a continuous surjection A′→XA′′. I don't know how to show that there is a topological space A with carrier set 2ω1 and a continuous surjection A→XA. Thanks to Alex Mennen for pointing out the problem.
1Rupert
When I look at my post the LaTeX code isn't formatting properly; if anyone can let me know how to fix that.