My wife changed her name.

I don't see the problem; we agree that Pluto hasn't changed, so we - meaning they - have decided to talk differently to make talk more self-consistent. Sometimes one might have to go into how Pluto was considered a planet and now is not - which you have done quite clearly enough.

And then we are all clear about what a planet is and how many there are, until they tell us they have changed our minds again.

So a thing's identity as an X is dependent on what we say of it? A thing is a planet only if we talk about it as such? A thing is a cup only if we talk about it as such?

A thing is what it is and we call it what we call it.

That doesn't really answer the question. Is there a difference between being a planet and being called a planet? If so, what is required for a thing to be a planet, and was Pluto ever a planet?

What is "a thing's identity"? There is the thing, and there is the way we talk, and then what else? It looks to me as if you want to reify the relation of name and thing in order to create a problem. Don't.

What is it that names name? It's not normally the material but the form. So you have created a misdirection in appearing to be talking about the material causes of Pluto - it's degrees of freedom - rather than its formal causes, or its informational constraints.

Then when it comes to the formal properties, we would need to make a further distinction between the natural form (what constitutes "a planet" as a naturally self-organising object/structure/process) and the human classification of forms (which can pick out natural form, but also picks out aspects of our own human scale interests).

So their are mountains, hills and molehills. As tectonic processes, they may have very similar formal causes. But in terms of reflecting the further thing of our human scale interests, there is an extra weight of information that a name would refer to.

This is one of the reasons why nominalism is so tedious and in all likelihood incorrect. Our language does not determine the identity of objects, the constitution of objects determine their identities, which our language describes in various ways. Languages can change all the time without the objects of predication changing.

I happen to be a composition-as-identity theorist, so whatever Pluto is, I see as dependent on every single part of whatever is seen as Pluto. A single change, changes the identity of Pluto from Pluto1.0 to Pluto1.1, for example. In fact I'm not even sure if I'm committed to objects in reality; I'm leaning towards conceptualist anti-realism or mereological nihilism.

What is "a thing's identity"? There is the thing, and there is the way we talk, and then what else? It looks to me as if you want to reify the relation of name and thing in order to create a problem. Don't. — unenlightened

A thing's identity is, for example, being a planet. What sort of conditions must be satisfied for a thing to be a planet?

On the one hand we might want to say that to be a planet is to have material characteristics A¹, B², and C³. It then follows that to have been a planet is to have had material characteristics A, B, and C. Given that Pluto doesn't have material characteristic C, it isn't a planet. And so given that Pluto has never had material characteristic C, it was never a planet.

But on the other hand it seems quite acceptable to say that Pluto was once a planet. If Pluto was once a planet then to have been a planet is not to have had material characteristics A, B, and C, and so to be a planet is not to have material characteristics A, B, and C.

So what's the answer? Was Pluto never a planet, or is being a planet not reducible to having material characteristics A, B, and C?

¹is massive enough to be rounded by its own gravity
²is not massive enough to cause thermonuclear fusion
³has cleared its neighbouring region of planetesimals

It all comes down to standards of measure and the time in which they're applied.

Pluto was considered a planet according to a standard of measure from a different time. Now we don't consider it a planet due to a refinement in that standard of measure.

Pluto still is... but what it is a relative to our standard of measure and the time in which we apply it.

Is there a difference between being a planet and being called a planet?

For whom or what? Me or Pluto?

What is required for a thing to be a planet?

I suppose this:

The definition of planet set in Prague, Czech Republic in August 2006 by the International Astronomical Union (IAU) states that, in the Solar System, a planet is a celestial body which:

1) is in orbit around the Sun,
2) has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
3) has "cleared the neighborhood" around its orbit.

* Now if you are watching a episode of "Rick and Morty" and you're Morty's dad, well...



Was Pluto ever a planet?

Well... it was considered a planet prior to this definition, so prior to 2006 I suppose we considered it a planet.

I sort don't think there is an fundamental intrinsic "planetness" that is a priori to the term planet. Any definition is bound by standards of measure and assumptions/attributions of value, so honestly definition are relative.

Sorry this probably doesn't help, but I'm not really sure you asked a question. What is a planet and what is considered (correctly according to the accepted definition) a planet are indeed both planets... until we decide to invent a new term or a new standard of measure; thus changing the definition. Pluto is still Pluto... unless we decide to change that, but I feel my point is drgging on here so I'll let it go.

Meow!

GREG

I happen to be a composition-as-identity theorist, so whatever Pluto is, I see as dependent on every single part of whatever is seen as Pluto. A single change, changes the identity of Pluto from Pluto1.0 to Pluto1.1, for example. — darthbarracuda

But this is a bad way of thinking about identity because it only names particular states of being, not general states of being. It is far too restrictive a form of classification for the act of naming to be informationally efficient.

Naming seeks to strike a balance between generality and particularity. You want to be able to point to the things you have in mind with the least communicative effort. So if you talk about "my cat", you don't want to have to talk about the great amount of molecular turnover that goes on so that my cat is - even a few seconds ago - was a materially different cat.

So your take on naming is based on the ontic commitments of a mechanist/reductionist view of things. You implicitly take stability for granted, making even the slightest change as something that could be rightfully named. It is presumed there are stable parts which have a particulate claim to identity. The world is a composite of such material/efficient causal particulars.

But a naturalistic metaphysics instead sees reality in terms of balances of plasticity and stability. And flux or change is basic if anything - when we are talking about the material causes or being, the constituting degrees of freedom.

So that is why - in a process or systems view - it makes more sense to focus on formal/final cause as the source of object/process/structure identity. We want to name whatever it is that maintains a consistent identity through time and can either weather change, or indeed, actively maintain a state of identity.

I guess the contrast here is between composition-as-identity theory and constraint-as-identity theory. ;)

Is there a difference between being a planet and being called a planet? — Mayor of Simpleton

To be a planet would be to talk about the natural process that "makes planetary objects". So we could narrow that to gravitationally produced lumps of heavy matter that are large enough/fluid enough to assume a gravitationally spherical shape (but not so large that they then collapse into black holes).

So if science is trying to decide if something is "really a planet", it would have to be a judgement in light of some theory that defines a natural process.

But humans then can add their own interests to a definition. Is it a planet if it is a gas giant with no where solid to land? Is it a planet if it is so small that you can walk around it too quickly, and it lacks enough gravity to hold you down properly? Is it a planet if it doesn't orbit a sun, but instead either wanders or perhaps is a moon that orbits a planet?

So naming always has this dual aspect - our attempts to speak of the world objectively, and then the degree to which we really want to work our own personal perspective into the naming of things.

So what's the answer? Was Pluto never a planet, or is being a planet not reducible to having material characteristics A, B, and C? — Michael

Again, it is the assumption that real things get reduced to lists of material particulars that causes the confusion.

If material properties are important to the form of some thing, then the formal properties will be the constraint that ensures the right materials are being used.

Is it necessary from a natural perspective that a planet is made of rock and not frozen gas? Well not if gravitationally compact and fluidly spherical are deemed key aspects of specifying "a planet" in naturalistic terms.

And gravity and spherical are formal properties, rather than material properties, in a physical description (even if folk still tend to think of gravity as a "material force" rather than spatiotemporal geometry).

So naming always has this dual aspect - our attempts to speak of the world objectively, and then the degree to which we really want to work our own personal perspective into the naming of things. — apokrisis

... but regardless of how objective we try to be, we are still fielding a value assertion according to an accepted standard of measure. Who fields the assertion and who fields the value assertions?

Indeed I will accept the definition of an authority and not just accept any position by anyone on the street. (I'm not a post-modernist, but like to use it as a check now and then.)

I suppose if I take to to the regress we all wish to avoid, what exactly makes a thing a thing?

As I understand this, a thing is a recognizable (by us) collage of strings (or loops or atoms or whatever is the smallest thing is found in everything... we're still refining that, so I'll drop that now) or an action/event that is in a pattern perceived consistancy context with a collage of strings (or whatever) that WE give a lable to as to make reference to this collage or event/action in context of a collage in the hope of having some sort of shared communication and conveying of ideas.

I know I can do better than that (it's late and I need to go to bed), but the point is WE define things... WE assert value. We can also misdefine things and assert value that is not really accurate... BUT accuracy and definition are still according to a standard of measure WE put into motion according to OUR experiences. As we experience more or refine knowledge of experience defintions, value assertions and standards of measure change/adapt/refine.

I don't ever rule out the possibility that our physics of today will be looked upon in the future as being near child's play. We've come a lot way, but certainly have a much longer way to travel. Definitions will continue to evolve as the standards of measure become more and more evoled.

So...

... what is a planet?

We can only answer this according to the current collection of knowledge we have and according to the best possible standard of measure in respect to this knowledge. As for an absolute answer... "please stand-by"... more informaton will be collected; thus refinement will occur.

... what is called a planet?

Actually the same thing, but also what one understands to be a planet, even if it happens to be outdated information, knowledge and standards of measure. Indeed this can be adapted as well, but sometimes it isn't. Not everyone really cares to be that exact and indeed it really might not make any difference to their lives, but hey... there's a lot of stuff out there to know and not a lot of time to get it all in one's head.

Meow!

GREG

... but regardless of how objective we try to be, we are still fielding a value assertion according to an accepted standard of measure. Who fields the assertion and who fields the value assertions? — Mayor of Simpleton

The point remains that our naming has the choice of either striving to talk about reality in a mind independent fashion, or in a fashion that is unabashedly subjective and seen from the point of view of our own interests.

So there are polar choices to be made. And we don't have to treat one as being then right, the other wrong. It is just important that there is this basic conflict in naming things - which then becomes a source of paradox if it is philosophically skated over, after the fashion of the OP.

I don't see any consistency in our naming. Pluto was a planet until some size queen decided it was too small. Perhaps Jupiter is not a planet because it is too big. Maybe it is a failed star. (Perhaps Jupiter feels it could have been a contender.) Why should gas bags like Saturn and Jupiter, and a small rock like Mercury all be planets? Maybe Ceres is a planet, since it is the largest of the non-planets within the orbit of Neptune. Gee whiz, shouldn't it get some credit for that? It was big enough to get itself together into a ball by dint of its own gravity, after all.

Pluto has suffered enough. Return it's dignity as a planet. FAIR PLAY FOR PLUTO!

Pluto, that rock with a location way out there, has not changed
'Pluto' the sound design has not changed
The only change is how we categorize it, its meaning has changed categorically.

Now we place it in the company of other similarly sized objects out there, which is where it should have been categorized if we had known its size when it was originally classified as a planet.

I think that the discourses of science, of technology are being continually mediated into culture. Its gone on this way since Copernicus. But then again, the sun still rises and sets.

Several years ago, I tried to define a planet. Maybe it was inspired by the Pluto issue, or maybe by something else. I can't remember. I started off convinced that of course there were sensible necessary and sufficient conditions for something to be considered a planet, and I just had to work hard enough to be able to articulate them.

I was very dismayed when, after much hard work and many scrumpled pieces of paper, I had to give up. IIRC the problem that finally stopped me was the question of at what point an oxygen molecule in space somewhere near the Earth stops being part of the Earth. No matter how hard I tried, I could not find a way to answer that which didn't involve drawing an arbitrary boundary, eg at a specified distance from the Earth's centre of mass. And I couldn't discard atmosphere because then a gas giant like Saturn would not be a planet.

I think these days I would - if challenged to do something like that - instead try to define a planet as a phenomenon (not an object - to avoid the problem of the atmosphere) and set different sufficient and necessary conditions for it. For instance a necessary condition might be that somewhere in the phenomenon there is a spherical region whose average density is greater than that of balsa wood, with a radius greater than 100km and less than the radius of the sun. But a sufficient condition might be that the radius is at least half that of Mercury. There will be a huge fuzzy region between that encompassed by the necessary conditions and that encompassed by the sufficient.

Pluto would be in that fuzzy region.

"Planet" conforms to anything that has an erratic movement in the sky, but looks like a fixed star other wise. All visible stars can be shown to rotate from a point near the Pole Star in a uniform circle.
The ancients noticed that some stars did not conform to this motion; demonstrating a retrograde motion. They were dubbed WANDERER, and that is how we come to have use of the word "planet". I see no good reason to down grade Pluto because of its size.

Watch "The Englishman Who Went up a Hill but Came down a Mountain", a partly fictional tale about a period when several survey standards still considered a "mountain" anything that was 1000 feet or 300 meter above the surrounding terrain. That standard now has several more criteria to distinguish it more clearly for survey standards. That doesn't prevent you from calling something a mountain that doesn't meet the definition. Also, it is possible that many places lost or gained "mountain" status. They were "mountains" under the old system, not "mountains" under newer systems and nobody can stop you from declaring something out of tradition.

Pluto is a "dwarf planet", which would make it sound like a kind of planet. The characteristics of Pluto make it unlike most other planets. Its orbit is elongated so it often comes closer to the sun than Neptune. It's the only solid surface planet outside of gas giants. It is more like distant objects in the Oort cloud than anything in inner rings. But it is smaller than most moons, including our own. It may sound like an arbitrary distinction, (you must be this tall to ride the roller coaster), but based on properties and characteristics important to astronomy.

It was once a "planet" under the old system. Probably partly because it was discovered at a time when astronomers were looking for a planet and did some publicity about discovering and naming it. They originally thought it was larger than Earth and they were looking for a "9th planet". Around the time Pluto was demoted to "dwarf planet", was when hundreds of new bodies in other solar system was being discovered and the question of what defines a planet was raised.

The second horn's conclusion doesn't follow – if Pluto is no longer a planet even though none of its relevant qualities changed, this doesn't mean to be a planet is to be named a planet.

Nouns seem to cluster around a family resemblance of canonical qualities, with a prototype and a fuzzy tolerance principle for how distant from that prototype an individual is willing to be before it no longer falls in the extension of the predicate. Language is sensitive to both the qualities required of the prototypical case and the level of tolerance allowed – as has already been adumbrated, the attitude verb consider is sensitive to this latter dimension without being sensitive to the former.

My answer would be, therefore, that what was changed was the tolerance allowed from the prototypical planet, which became more restrictive in such a way that Pluto now falls outside of the extension (though only for a technical community – I'm sure many people still consider Pluto a planet and there seems to be no scientistic reason to say they're wrong, after all the language has the say, not the scientists; the effect only happens to the extent the language puts up with the scientists and decides to obey them). This does not mean that the naming of Pluto as a planet or not has some power to make it a planet or not (which is obviously absurd), nor does it mean that Pluto, or the core characteristics of a planet, have changed in some appreciable way (with e.g. Jupiter remaining a canonical example as it ever was).

If "planet" is a definition, a purely abstract, non-physical set of criteria, then an object is classified as a planet if those criteria are satisfied. The object (the actual physical thing we see in the sky) is a planet if those criteria are met, regardless of whether we identify it as such. That means there are many other planets we don't know about and have never spoken about, and there may well be many objects we call planets that are not. If when I say "planet" I mean it has criterion X, and I refer to an object as a planet that lacks X, then I am simply wrong.

This does not mean that the naming of Pluto as a planet or not has some power to make it a planet or not (which is obviously absurd) — The Great Whatever

That depends on what it means to be a planet. If to be a planet is to have certain material characteristics then the claim that naming Pluto a planet makes it a planet is the claim that naming Pluto a planet makes it have certain material characteristics, which of course is absurd. But if to be a planet is to be named a planet then the claim that naming Pluto a planet makes it a planet is the claim that naming Pluto a planet makes it named a planet, which of course is a tautology.

Nouns seem to cluster around a family resemblance of canonical qualities, with a prototype and a fuzzy tolerance principle for how distant from that prototype an individual is willing to be before it no longer falls in the extension of the predicate. Language is sensitive to both the qualities required of the prototypical case and the level of tolerance allowed – as has already been adumbrated, the attitude verb consider is sensitive to this latter dimension without being sensitive to the former.

My answer would be, therefore, that what was changed was the tolerance allowed from the prototypical planet, which became more restrictive in such a way that Pluto now falls outside of the extension

So to be a planet is to fall within the tolerated extension of the word "planet"? Wouldn't we then say that in naming Pluto a planet we are making it the case that Pluto falls within the tolerated extension of the word "planet"? And so that in naming Pluto a planet we are making it the case that Pluto is a planet?

So the question is; what is criterion X, and has Pluto ever met it? If criterion X is some set of material characteristics, and if Pluto has never had these material characteristics, then Pluto has never been a planet.

That depends on what it means to be a planet. If to be a planet is to have certain material characteristics then the claim that naming Pluto a planet makes it a planet is the claim that naming Pluto a planet makes it have certain material characteristics, which of course is absurd. But if to be a planet is to be named a planet then the claim that naming Pluto a planet makes it a planet is the claim that naming Pluto a planet makes it named a planet, which of course is a tautology. — Michael

But calling something a planet doesn't make it so; therefore it can't be that to be called a planet is to be a planet.

So to be a planet is to fall within the tolerated extension of the word "planet"? Wouldn't we then say that in naming Pluto a planet we are making it the case that Pluto falls within the tolerated extension of the word "planet"? And so that in naming Pluto a planet we are making it the case that Pluto is a planet? — Michael

To be a planet is to fall within a tolerated distance from a fuzzy prototype whose conglomeration of qualities is that which is currently referred to by the word 'planet.' Being a planet has nothing to do with being called by a certain word. The fact that the right prototype or selection of qualities happens to be referred to by that word is purely accidental. In naming Pluto a planet, we are making the case that it is a planet, but not that it is called a planet or that it falls within the extension of a certain word, which is absurd (although the two will extensionally, not intensionally, overlap in worlds in which 'planet' refers to the property of being a planet, which it need not).

But calling something a planet doesn't make it so; therefore it can't be that to be called a planet is to be a planet. — The Great Whatever

Whether or not calling something a planet makes it so is the very question I'm asking (so obviously to address it you can't simply beg the question and assume otherwise). The case that could be made is that a) 20 years ago, Pluto was a planet, that b) today, Pluto isn't a planet, and that c) the only relevant change between 20 years ago and today is in what things we name "planet". It then seems to follow that to be a planet is to be named a planet.

So if you reject the conclusion then you must reject one of the premises. You seem to accept b) and c), so do you not accept a)? Was Pluto not a planet 20 years ago?

To be a planet is to fall within a tolerated distance from a fuzzy prototype whose conglomeration of qualities is that which is currently referred to by the word 'planet.'

And what has to change for a thing that once fell within the tolerated distance to fall out of it (or vice versa)? Presumably a change in material characteristics is one. But that's not what happened to Pluto. What changed was our use of the word "planet". So our use of the word "planet" influences whether or not Pluto falls within this tolerated distance, and so influences whether or not it is a planet.

Pluto was a planet when we used the word "planet" to describe things like it and it's now not a planet given that we don't use the word "planet" to describe things like it.

There is a threshold of mass above which gravity ensures that agglomerated celestial objects become, at least in appearance, spherical. I think that would be the best criterion for planethood.

Under this crierion alone, though, many moons would be counted as planets; so another criterion, "that to be counted as a planet, a celestial body must orbit around no other body than a star", would need to be added.

Whether or not calling something a planet makes it so is the very question I'm asking. — Michael

But this is obviously false. If I call a stove a planet, it is not therefore a planet; it's just a stove, that I'm calling a planet. So I'm a little confused as to how this is even a question for you.

Are you proposing that this is a realistic definition of 'planet'?

For all x, x is a planet iff x is called a planet

I want to get this clear, because this the above definition has some pretty obvious flaws. I think it's self-evidently wrong, but if you aren't convinced, we can hash it out.

So if you reject the conclusion then you must reject one of the premises. You seem to accept b) and c), so do you not accept a)? Was Pluto not a planet 20 years ago? — Michael

Using my own English idiolect, I would still call Pluto a planet. A technical community has deemed that it isn't, by some standard. By that standard, it never was a planet. According to the ordinary use of the word, at least as I use it, Pluto always was, and still is, a planet, and the decisions of a technical community don't change that. (Words, generally, do not have their extensions based on council decisions).

And what has to change for a thing that once fell within the tolerated distance to fall out of it (or vice versa)? Presumably a change in material characteristics is one. But that's not what happened to Pluto. What changed was our use of the word "planet". So our use of the word "planet" influences whether or not a thing falls within this tolerated distance, and so influences whether or not this thing is a planet. — Michael

As I said, nouns are sensitive both to a cluster of properties instantiated by the prototype (for a planet, plausibly material properties), and a tolerance allowed in the consideration of at which distance from that prototype the property ends, based on a fuzzy tolerance principle. 'Planet' is sensitive to both simultaneously, and different attitude verbs pick this out. Thus, if I say, 'I believe Pluto is a planet,' I plausibly mean that Pluto has some physical characteristic that falls near enough to the prototype. But if I say, 'I consider Pluto a planet,' I do not mean that Pluto has any material qualities but that given the material qualities it actually has, the tolerance principle of the property of being a planet admits Pluto within it.

Our use of the word 'planet' governs which property the word 'planet' refers to. It does not govern the property itself, nor whether any individual bears that property. To think otherwise is a deep confusion.

I agree with what you say, against the idea that naming is totally arbitrary and determinative of the ontological status of things; but the criteria for deeming a thing to be a table are perhaps more readily obvious than the criteria for contending that something is a planet.

Our use of the word 'planet' governs which property the word 'planet' refers to. It does not govern the property itself, nor whether any individual bears that property. To think otherwise is a deep confusion. — The Great Whatever

I agree. But the question is; is to be a planet to have this property?

If to be a planet is to have this property, and if Pluto has never had this property, then Pluto has never been a planet. But if Pluto has been a planet, and if Pluto has never had this property, then to be a planet is not to have this property.

But this is obviously false. If I call a stove a planet, it is not therefore a planet; it's just a stove, that I'm calling a planet. So I'm a little confused as to how this is even a question for you.

It's not that a stove is a planet if I call it a planet; it's that a stove is a planet if the wider linguistic community uses the word "planet" to refer to stoves. Because in such a world the words "planet" and "stove" would mean the same thing (and so the word "planet" wouldn't mean what it does now).

Obviously I'm not saying that if I call a stove a planet then it is therefore a celestial body moving in an elliptical orbit round a star. As I agreed before, it would be absurd to claim that the act of naming can change the material characteristics of the thing named.

I agree. But the question is; is to be a planet to have this property? — Michael

Yes. To be a planet is to be a planet; not to be called a planet.

If to be a planet is to have this property, and if Pluto has never had this property, then Pluto has never been a planet. But if Pluto has been a planet, and if Pluto has never had this property, then to be a planet is not to have this property. — Michael

I do not think that at any point in human history Pluto became, or ceased being, a planet. Part of the confusion here I think is we're trying to treat linguistic practice as if it rested on decisions made by experts, which it doesn't. The Pluto decision is interesting in that a lot of people heard about it via the media and at least nominally in some cases defer to it. I think if you pressed people enough they'd say that the notion that Pluto stopped being a planet at some point doesn't make sense. What happened was that a group of scientists decided that Pluto wasn't a planet; since they did this by appealing to physical aspects of Pluto, not what Pluto was called (which would make no sense), their position is that Pluto was never a planet, so if the authority is deferred to, one would have to agree with it on this score. I think you might be treating your initial purported data a little too seriously, and that when pressed it falls apart. As I said above, I personally would still say Pluto is a planet, since my idiolect isn't governed by the decisions of scientists.

It's not that a stove is a planet if I call it a planet; it's that a stove is a planet if the wider linguistic community uses the word "planet" to refer to stoves. — Michael

So you think that a stove can become a planet if everyone uses the word 'planet' to refer to it?

Doesn't that strike you as an absurd position? If not, we may have to dig a little deeper into why you think this. It strikes me as completely insane. I'd say myself it's still just a stove, and obviously not a planet; but now the word 'planet' can be used to refer to stoves, is all.