Back   

2009-04-30
What is a relation?
I would like a criterion of polyadicity. What jumps to mind is that polyadic properties require more than one object for their instantiation. But that's not true of some paradigmatic polyadic properties, for example, resemblance (everything resembles itself, so there doesn't have to be two objects for there to be resemblance). While the fact that a property is instantiated by two objects (together) seems like a sufficient condition for polyadicity, it is not necessary. A few hours of searching through PhilPapers, SEP and Scholar have not revealed anything more promising--have revealed very little discussion of the matter, in fact.

I have a sense that this is relevant: you can generally have more possible instances of a polyadic property with N objects than you can have instances of monadic properties with the same number of objects, because you get a combinatorial explosion of possible instances. Having said that, I don't know how to finesse this observation into a criterion of polyadicity.

PS: One might be tempted to say that a n-ary property is a set of n-tuples. But that seems to be merely a way of modeling n-ary properties. I would like a criterion applicable in the wild.

2009-05-03
What is a relation?
Reply to David Bourget
I think the suggestion in the postscript is the way to go but I'm not sure what kind of criterion you're after-- where is the wild?

Perhaps good properties to think about here are identity and self-identity. The relation of identity and the monadic property of being self-identical are in an attenuated sense instantiated by the same objects (i.e. the former by every object and itself and the latter by every object) but the set of tuples that is (or represents) the relation of identity will have more members than the set of tuples that is (or represents) the monadic property of self-identity. 



2009-05-03
What is a relation?
Reply to Brian Rabern
Hi Brian. By "in the wild" I had in mind philosophy outside of logic. To pick a random example, there's a view I'm attracted to in philosophy of mind according to which phenomenal properties are relational properties of a certain kind. Accordingly, I'm trying to clarify what the cash value of saying that they are relational properties might be. A relational property is not supposed to be a relation but a property like "standing in relation R to X", for given R and X, for example, standing in the resemblance relation to a cat.

I find the tuple answer irrelevant because one could well model relational properties as sets of objects--or one could model them as sets of ordered pairs of objects. The choice of model seems arbitrary.

2009-05-03
What is a relation?
Reply to David Bourget
I see. Armstrong talks about "impure predicates", i.e. those which involve essential reference to a particular (e.g. `descended from Charlemange'). And I thought when people talk about `relational properties' they mean something like a property which makes ``essential reference" to some object like being identical to Cicero. A first pass might be this: F is a relational property iff x's having F consists in x bearing a relation R to something y (with certain fixes to make it non-trivial).

So there is an easy translation between relational property talk and relation talk. But I don't think that makes anything arbitrary -- relational properties are sets of objects and relations are sets of ordered pairs of objects.

I'll have to think more about how this relates to phenomenal properties as certain relational properties. 

2009-05-04
What is a relation?
Reply to David Bourget
Lloyd Humberstone's 1996 paper "Intrinsic/Extrinsic" (Synthese 108: 205-67) contains a very good discussion of three different versions of the distinction between intrinsic and extrinsic properties: intrinsic properties as non-relational properties, intrinsic properties as purely qualitative properties, and intrinsic properties as interior properties . The relevance here is that Humberstone shows why the relational/non-relational distinction is not a very good stand-in for the intrinsic/extrinsic distinction, in part by making a point similar to the one you raise here: the property of being identical with oneself is both a relational property (identity being a relation) and an intrinsic property. And he concludes with a discussion of the question of whether the three distinctions distinguish 'properties'  in the same sense of 'property'. I highly recommend this paper.

Steve Gardner

2009-05-05
What is a relation?
Reply to Brian Rabern
Hi Brian. My problem is not so much with how to analyze the notion of a relation property--I'm happy to define them in terms of your proposed analysis (that's what I did in my second post). My problem is this: how can we determine when it's the case that x's having F consists in x bearing a relation R to something y? Take weight. Is weighting 50 kg a relational property? One might say that weighting 50 kg consists in standing in the weighting-in-kg relation to the number 50. But is this really clear? This might seem like the start of a slippery slope. For example, one might go on to add that being red is standing in the instantiation relation to redness.

So, what I'm trying to do is determine when it's legit to say that a property F consists in bearing a relation to something. I'm increasingly tempted to take a deflationist stance: it's always legit, so long as you allow instantiation as a relation and non-individuals as relata. If you don't allow instantiation as a relation, there might be some constraints, but it's not clear what the rationale would be for doing this (some kind of Bradley's regress?). It's also not entirely clear that there would be a constraint: one might say that being red is standing in the having-color relation to redness. All "relations" which consist in part in instantiation would have to be banned. This may or may not work. This might seem too strict. For example, this might seem to ban being the same color from relations. What might well work is to ban non-individuals as relata. However that would yield too restrictive a notion of relational properties for my purposes.

I'm going to have a look at the paper Steve mentions (thanks for the pointer!).

By the way, it's possible to cite PP entries direct in posts, like so: Humberstone (1996)

(You enter "e#[ID]", without quotes and with [ID] replaced by the paper's ID. There is a utility for finding papers and adding these codes in the editor ("Cite").)

2009-05-05
What is a relation?
Reply to David Bourget
I've come late to this discussion, and I'm sorry if I am being irrelevant, but aren't there two questions here?  The first is: how many places does a predicate have?  The second is: what's the proper predicate-calculus analysis of a predicate "in the wild"?

With respect to the first question, predicates simply come with a given number of places.  It's part of how they are defined or introduced.  It isn't a matter of philosophical effort. 

That said, there are certain standard ways of reducing the polyadicity of a predicate.  One of them is to force a variable to be instantiated a certain way.  Thus: Rxy is two-place, but Rxx is one place (for the same R): thus identity is two place (though x=y is true only when the first and second variables are instantiated by the same thing), but self-identity -- 'x=x' is one-place.  (Substitute similarity for identity, and the same holds.)  Another way is to specify a value for one variable: for example, weight in kilos, K, is a two place relation: K(x,y), which is true iff y is the weight of x in kilos.  However, K(x,50) is a one-place predicate, and true of all and only those things that weigh 50kg. A third way if to bind one of the variables.  Thus, ExKxy is a one-place predicate meaning "Something has weight y (in kilos)".

With respect to the second question, there have been a lot of answers.  Roughly: if R is a "wild" predicate, and if you can get Ra and not-Ra without equivocation, then a standard move is to suppose that R has at least one more place, and that Ra is elliptical for Rab (for some b), while not-Ra is elliptical for not-Rac, for c not equal to b.

Is there a problem with this simple-minded answer?



2009-05-06
What is a relation?
Reply to Mohan Matthen
Hi Mohan, thanks for this, it's very helpful. There were two questions indeed, and I think you gave very good answers to both. Your no-contradiction test at the end sounds like just what I needed. I'm curious to know more about it. Do you have any references I can look up on this? Please don't tell me it's in the Brown Book, I will feel foolish! :)


2009-05-06
What is a relation?
Reply to David Bourget

Hi David,

For relations in extension (RIE), the question boils down to sets whose membership is defined in the usual way.  Relations in intension (RII) are something else.  I agree with you that the tradition of linking logic to ontology here is a bad idea, i.e., it's a property if it's exemplified by one thing, otherwise it's an RII.  The matter came to a head for me many moons ago when I was thinking about the Russell Paradox.  If we allow "~(x exemplifies x)" as a substitution instance for an abstraction axiom for properties, his famous argument goes through and we're dead.  The gambit I tried is to define (contra Frege) n-adicity-in-intension based on variable occurrences rather than variables: intuitively, one variable occurrence is a property, otherwise it's an RII.  Russell's sentence expresses a funny kind of relation, not a property, so property abstraction is okay.  I also used this idea to resolve the Third Man Argument's hang-up over self-exemplification -- the point being that Plato should have anticipated Russell's non-self-exemplification "property," so the solution to the Russell Paradox should also fix Plato's TMA.  I need to post on this site references to the papers I published on this stuff years ago -- maybe over the weekend.

Cheers,

Arnold    


2009-05-06
What is a relation?
Reply to David Bourget
Hi David.  There are a number of places in the literature where the no-contradiction test is used.  There was an extended discussion in the seventies of Protagorean relativism in the Theaetetus (See Burnyeat 1976, 1976 and my own piece in Dialogue 1985), as well as of Plato's use of the no-contradiction argument in arguing for the changeability of worldly particulars (Matthen 1984).  Jonathan Cohen discusses such an approach to colour in 2003.  There is discussion relating to your original question by Donald Davidson in "The Logical Form of Action Sentences", where he converts Kenny's idea that action sentences are "variably polyadic" 1963 into a whole paradigm of event predication, which is taken in a new direction by Paul Pietroski, perhaps here: 2008.

You can see, by the way, that I had both fun and failure with the cite function.

Mohan

2009-05-07
What is a relation?
Reply to David Bourget

As of the back and forth on this thread it appears you were asking a question in relational logic, not metaphysics. For the record, the answer to which you took apparent exception was a metaphysical response that was quizzical for what proved to be the right reasons. Audi’s Dictionary of Philosophy suggests some of the relevant distinctions (under ‘relation’).

In relational logic, I believe we can define polyadicity quite simply as follows: The differential distribution of a property. Whatever receives the property is, by the semantics, forcing a polyadic facticity. Note that in relational logic it is property that is employed to define relations. But the real definition of the plural aspect appears to require the distinction herein offered up for further discussion by your readers.

Note, however, why a metaphysician tends to question such methods of definition. I stressed the word ‘receives’ to suggest that where one element is passive, another is presumed transitive or otherwise active. But is it the “relation” that is active? Or is the “relation” merely a label by which to describe the presence of what is taken to be epistemic? The fallacy of realist attribution looms large and is obviously best avoided, which is why in my first attempt I didn’t “go there”. I am, however, a ‘soft’ realist myself, and I wish not to imply a nominalist persuasion by these comments.

In utilizing the comparative weight issue you are doing the same as asking of the image (in a mirror, for example) with respect to the original. In either instance we have, as doubtless you are aware, the reflexive type, R such that for ‘a’ and ‘b’ aRb, 'a' weighs the same as 'b', 'a' appears the same as 'b', etc. Unfortunately, this does not (properly in my estimation) define either identity or plurality, and is yet another reason to be overly careful in taking relational logic too seriously.

What happens when an adjective comes to take on the character of the noun it modifies, or when a noun takes on adjectival properties of its grammatical modifier? Where are we with relational logic? We are at square one, or nearly so. Indexical v. indexicality, philosophic v. philosophical. What distinguishes each member of the pair from the other if not what I have just described? How can we make relational logic account? I believe there are possible ways, but I am not certain anyone in love with relational logic will be ready to listen anytime soon. As for methods claimed to work, I am distrustful. There is something slightly irrational in these cross-fertilizations, and most forms of logic are practically by definition ill-equipped to handle anything between here and the Andromeda nebula as regards the irrational.

From the vantage of metaphysics, what might happen were these considerations to become relevant to the discernment and definition of plurality in relations. How would the “differential distribution” notion have to be modified, if at all? For example, would we be required to assert specific properties, for example: Pervasiveness? Penetration?  See-through? Governance? The problem, of course, is that elements within cognatic dyads might not easily fall into the usual categories of relation as defined in relational logic. This is where I was coming from the first time around, sorry for the misimpressions conveyed. Anyhow, just a thought. Have fun.

CSH


2009-05-30
What is a relation?
Reply to David Bourget

BIG, BIGGER, BEST: ON ABSOLUTE VS. RELATIVE JUDGMENT

DB: "I would like a criterion of polyadicity. What jumps to mind is that polyadic properties require more than one object for their instantiation."
Okay, I'll bite, but only for epistemic aspects of properties/relations, not ontic ones -- i.e., not about what properties/relations are, but about the conditions under which people judge things to have properties or relations. For my example, I will use "big" and "bigger."

The inclination is to say that being "big" is a monadic, absolute property and being "bigger" is a dyadic, relative property, requiring at least two things to be compared.

The problem is with "thing." For I can certainly look at a circle alone and judge that it is big. And I can look at a second circle alone, and judge that it is big too. And I can also compare the circles, and judge that the second circle is bigger than the first circle.

So far, everything is in conformity with the idea that properties are monadic and absolute, whereas relations are polyadic and relative. 

But I can also consider the two circles as one composite object, and I can judge that composite object to be "plus" if the bigger circle is on the right and "minus" if the bigger circle is on the left. So being plus or minus is a monadic, absolute property, yet it is based largely on the same judgment that we just called relative.

There is a tug toward saying that the plus/minus judgment has a relative component because it is based on a sub-thing judgment that is dyadic and relative. But there the cognitive phenomena of "subitizing" and "overlearning" suggest that this too may be an oversimplification:

"Subitizing" occurs when a property immediately "pops out" holistically, rather than as a result of a slower sequential analysis. A good example is counting: If we see a few discrete objects, we can count them, and the more there are, the longer it takes. But when there are only 1-4 objects, we can detect their "numerosity" (cardinality) instantly, without counting, from their (absolute) "shape."

The capacity to subitize cardinality 1-4 without counting is probably inborn, but subitizing in general can also be learned. Often we will be able to subitize after we have practised, through repetition, to detect a property through slow, sequential analysis, and then we continue learning -- "overlearning" -- until the detection becomes as fast and unconscious as a reflex. The plus/minus judgment described above could almost certainly be overlearned to the point where it is subitized.

The reply may be that although one is not conscious of the comparison process implicit in the plus/minus judgment, it is nevertheless going on, unconsciously. One might also argue that there is unconscious counting going on in the case of subitizing 1-4. But it is much more likely that what has happened is the kind of recoding that, since George Miller's celebrated paper on the "magical number 7 +/- 1" has come to be called "chunking" and "rechunking": The brain simply recodes what it takes to be a "thing": In the case of 1-4 judgments, this chunking is innate; in the case of perceptual overlearning, it is learned, but the resultant property "detector" is much the same: it detects what would otherwise seem to be a series of simpler properties as a single complex property.

Miller did make an important distinction between relative and absolute judgment, however. An absolute judgment is made on the basis of a single thing (usually presented as a sensory stimulus or "input"), whereas a relative judgment is made on the basis of two or more things, presented simultaneously or successively. "Big" would then be an absolute judgment, whereas "bigger" would be a relative judgment. Miller's interest, in that paper, was in information, which is the reduction of uncertainty, and in particular he was interested in the limits of our capacity to reduce uncertainty in the case of relative and absolute judgments.

The limit on relative judgments (in each sensory modality) is the "just noticeable difference" or JND. Miller pointed out that the size of the smallest difference we can discriminate relatively, and hence the number of JNDs, is largely immutable and depends on the sensory modality and the property dimension in question, as constrained by the inborn sensitivity of our sense-organs and brain. 

In contrast, Miller pointed out, the size of the "chunks" we can identify absolutely seems to be 7 +/- 2 (since revised downward by Maxwell Cowan to something closer to 4), but that limit can be increased substantially by recoding more information into a single chunk through overlearning. His famous example was digit span, in which we can usually only repeat by rote a series of about 7 random 0/1 digits we have heard or seen. But if we learn (and overlearn) how to recode the 0's and 1's into composite binary code, using our overlearned decimal names for the cardinal numbers, till we can reliably subitize the decimal names for triplets of 0/1 digits (much the way we can recode dots and dashes in morse code), then we thereby increase the number of 0's and 1's that we can remember considerably. (In the case of morse code, we can extend it to the number of random words we can remember by rote, again about 7 +/- 2 -- and presumably even more if the words make sense.)

There is more: Even "big" is an implicit relative judgment. (That is why I chose it.) It presupposes some sort of a comparative scale as a context. A circle the size of a quarter is big relative to the size of atoms and small relative to the size of planets. We often have an implicit ("subitized") default context for absolute judgments of degree, but that still leaves what first looked like an absolute judgment now looking like an implicit relative judgment instead.

But aren't all absolute judgments like that? There's an old Maine joke that speaks volumes about relative vs. absolute judgment: "How's yir wife?" Reply: "Compayured to whot?"

Even shape detection -- say, circle vs. non-circle -- has an implicit background context, which will result in different judgments when the context of alternatives amongst which uncertainty needs to be minimized is circles vs. elipses and when the context is circles vs. squares. One context or the other (or both, if cued) can likewise be overlearned to the point where it is subitized.

The upshot seems to be either that (1) whether a judgment is absolute or relative depends on what chunks the observer has overlearned to subitize or (2) all judgments are implicitly context-dependent, hence always relative, never absolute.

I have not provided the requested criterion of polyadicity (but perhaps I have given some reason to think we may not need one). 

(And I remind you that this was all based on the epistemic, not the ontic properties of objects and properties, as detected by sensorimotor systems like ourselves. On the ontological status of properties and "relations,", nolo contendere.)

-- SH

Harnad, S. (1987) Category Induction and Representation, Chapter 18 of: Harnad, S. (ed.) (1987) Categorical Perception: The Groundwork of Cognition. New York: Cambridge University Press.

Harnad, S. (2005) To Cognize is to Categorize: Cognition is Categorization. In Lefebvre, C. and Cohen, H., Eds. Handbook of Categorization. Elsevier.  





2009-06-04
What is a relation?
Reply to David Bourget
Charles Sanders Peirce approached the matter of relations and relative terms in a way that gave equal weight to comprehension (what we loosely call intension today) and extension, resolving their duality in the medium of a third something he called information.  He also gave an account of hypostatic abstraction, the process by which we posit a property common to all and only those tuples in the extension of a concept.

A sampler of readings below, most of them eternally in progress:

Hypostatic Abstraction @ PlanetMath

Relation Theory @ PlanetMath (may not work due to system changeover)

Relation Theory @ PlanetPhysics (try this link if the one above is broken)

Peirce's 1870 Logic of Relatives (my very rough working notes)

Jon Awbrey

2009-06-04
What is a relation?
Reply to Stevan Harnad
I am not sure what the bottom line of Stevan's interesting post is.

Let's define:

(1) Br (x, y) iff x is a circle and y is a circle and either x is on the left and x is larger than y or y is on the left and y is larger than x. 

By definition, Br (x, y) is a relation.

Suppose that we now introduce a class of objects,

C: x belongs to C just in case x is the mereological sum of y and z, where y and z are circles.  Here I'll call the circles y and z, the "privileged parts" of x.  (The calculus of individuals mandates that parts of y and z will also be parts of x, and of course there will be circular parts of y and z -- that would pose a problem in what I am just about to do, and this is why I have introduced the notion of privileged parts.)

Now, we introduce a new predicate B as follows:

(2) B(x) iff x belongs to C (i.e., if x is the mereological sum of two circles), and for all y, z such that y,z are privileged parts of x, Br (y, z).

By definition, B(x) is monadic.  It is derived from Br (x, y) by introducing a new variable, and binding the variables of Br.  (2+1-2=1)

I THINK Stevan wants to say further that untutored perception delivers (1) through subitizing, but we can learn to make quick judgements of the form (2) by overlearning.

So far, I think I have adhered to Stevan's intentions.  But I am not very clear what he means when he says that we don't need a criterion of polyadicity.  We are discussing two predicates, one is a relation by definition, the other is monadic by definition.  We are applying a criterion of polyadicity.



2009-06-04
What is a relation?
Reply to Mohan Matthen

What I am suggesting is that if you look at objects and properties epistemically rather than ontically -- i.e., in terms of how the brain sorts its sensorimotor inputs, rather than in terms of what objects and properties generate those inputs -- it is not clear whether a criterion of polyadicity is still needed (or perhaps whether it's always needed): What looks relational when described ontically may be holistic (monadic) epistemically.

Another way to put it is that there are ontic objects out there, but the "objects" that the brain actually operates on depend on how the brain has learned to categorize and chunk its inputs. What is polyadic and relational out there, might be monadic and nonrelational for the brain.

And, most important, the brain's "objects" and properties are not immutable: they can be rechunked.

(In my ignorance of formal work on properties, relations and mereology, though, I wonder whether, for example, the distinction between isosceles and scalene triangles is based on a monadic property of triangles or a relational property of sides.)

(One correction: the kind of subitizing and "pop-out" that I was referring to was a result of overlearning, rather than an alternative to it. The slower, serial, analytic (and usually more conscious and deliberate) processing is what occurs before and during the learning and overlearning, whereas the automatized, holistic processing happens after the overlearning.)

-- SH


2009-06-04
What is a relation?
Reply to Stevan Harnad
David's original question had to do with how you determine whether a concept is monadic or relational.  Take the concept BIG.  What is the criterion that makes us say that it is relational, or not.

Stevan in slightly different territory, if I am not mistaken.  He is asking whether a given situation -- e.g. the situation of the left of two circles is bigger, or the situation that a triangle is isosceles -- is best described relationally or monadically.  The first question bears on the second: for if you determine that BIG is relational, then there wouldn't be any way of describing the bigness of David monadically.  However, it is often the case that one and the same situation can have alternative descriptions, and I was trying to illustrate this with the example of the left-circle-being-larger.  The same goes for the isosceles triangle: this is a situation that can be expressed in more than one way. 

In these situations, the relationality is certainly not ontic, but isn't exactly epistemic either.  It is, if you like, a matter of choice -- choice about how you describe a situation.  (This is presumably what is meant by the term 'rechunking'.)  Of course, the brain may "choose" one rather than another, as Stevan says, and this "choice" will have epistemic consequences.

Question about subitizing: isn't there evidence that some subitizing procedures are innate? 

2009-06-04
What is a relation?
Reply to David Bourget
I'm in broad agreement with Mohan's response to Stevan's insightful comments, I think, but I would put things a bit differently.

SH: (1) whether a judgment is absolute or relative depends on what chunks the observer has overlearned to subitize

It's clear from the evidence you discuss that a given scene can be "seen" in different ways. Look at the scene one way, you see one big object bearing a monadic property; look at it the other way, you see smaller objects related to one another. But I'm inclined to say that all this shows is that one does not have to see all the facts about a scene at once (or all the objects and properties in a scene at once). Put differently, I think the relative and non-relative judgements in your examples can be correct at the same time. I don't think it follows from this that there is no fact of the matter about which properties are relational or not. What this shows is that relational and monadic properties are closely related, and that there are lots of objects around in addition to the most noticeable ones.

SH: (2) all judgments are implicitly context-dependent, hence always relative, never absolute.

I think we can distinguish between contextual and relative judgements. Plausibly, the concept BIG is contextual in this sense: the property that you are ascribing to something when you use the concept varies from one occasion to another (from one context to another). Sometimes you mean big-for-a-mouse (e.g.. bigger than 10x10x10xcm), sometimes you mean big-for-an-elephant (bigger than 2x1x2m), etc. This is compatible with each property you ascribe when you use BIG being a monadic property. I think that account of contextual terms/concepts is pretty standard, though I'm not a specialist.

(Having said this, if being big in any context is always bearing a relation to a number it could be a relational property, but this would be for a different reason than the one you brought up (and that's one of those tricky cases where a criterion of polyadicity would be helpful).)




2009-06-05
What is a relation?
Reply to Mohan Matthen

SUBITIZING, INNATE AND LEARNED


MM: "isn't there evidence that some subitizing procedures are innate?"
Yes, subitizing cardinalities ("numerosities") 1-4 is innate. (Some animals can do it too.) But I was focusing specifically on learned subitizing as a consequence of overlearning. (People can be trained, for example, to subitize somewhat more than 1-4, but not much -- with the exception of autistic savants, who allegedly subitize much higher cardinalities, and with no particular training.)


-- SH

2009-06-05
What is a relation?
Reply to David Bourget
Maybe the question of adicity (some say arity) can be put in relief by contrasting relations that have a fixed arity with those that do not.

For example, a formal language L is a particular subset of the set of all finite strings on a finite alphabet A.  One writes:  L subset of A*.

We may view a sentence of L as having some mysterious quality of grammaticality that it shares with all the other sentences of L, which property may be the job of a language learner to suss out from a more or less impoverished sample of examples.

But we may also view the sentences of L as tuples of finite but various lengths, construing L as a generalized type of relation with no fixed arity overall.

2009-06-05
What is a relation?
Reply to David Bourget
David is right to say that "there are lots of objects around in addition to the most noticeable ones", and lots of properties too.  That the composite object consisting of two circles has a certain property P is a different fact from that of the two circles standing in a certain relation R.  Of course, these may be logically equivalent -- but they are still different.  If they are logically equivalent, the situation is completely described either way -- one of these fact allows you to derive the other(s) by logic alone.  And as David points out, this is compatible with saying that it is an objective fact that P is monadic and R dyadic.

Context similarly determines which property you are attributing to something.  In one context you mean BIG (x, MOUSE); in another you mean BIG (x, ELEPHANT).  These properties are different and they are monadic, but each is derived from an underlying relation BIG (x, y) by giving the free variable y a value.  What is the criterion that makes me say so?  Well: isn't it intuitive to suppose that there is a common element in the above-mentioned properties?  My claim accommodates and explains this intuition. 

In general, how you translate terms of ordinary language into a formal language is a matter of explaining such intuitions, but there is no uncertainty concerning the form of the formal language -- that is simply given when the language itself is specified.  Again: translation isn't governed by criteria; it is a matter of explanation.

This last point helps clarify something that Jon said.  Given a natural language, we need to figure out how to translate into a formal language, and there may be more than one way to do so.  But it is misleading to say that with a formal language, e.g. the first order quantificational calculus (QC), there is any uncertainty about the structure of a well-formed formula.  There are no predicates of indeterminate adicity in QC.  We know that because we defined QC.  If English can be shown to have such predicates, then English can't be translated into QC (or into second order logic either, in which there are similarly no predicates of indeterminate adicity).  And this is a motivation for getting rid of indeterminate adicity for English, or for defining a new formal language in which there are such predicates (or for giving up the translation project, I suppose). 

2009-06-07
What is a relation?
Reply to David Bourget

CATEGORY INTERCONFUSABILITY AND THE CONTEXT-DEPENDENCE OF CATEGORIES

DB: "...a given scene can be "seen" in different ways.. one way, you see one big object bearing a monadic property... the other way, you see smaller objects related to one another... [R]elative and non-relative judgements... can be correct at the same time. I don't think it follows from this that there is no fact of the matter about which properties are relational or not... we can distinguish between contextual and relative judgements..."

If I could put it in slightly more specific language: Yes, a given input can be categorized in different ways (and, because of categorical perception effects, this also means it can be "seen" in different ways), depending on context. 

But there is a very specific reason why the context-dependence of all categorization (with the possible exception of what is based exclusively on a stipulated formal definition) entails that, in a sense, all category judgments are relative rather than absolute: To be able to categorize correctly you have to be able to sort the category members correctly from the nonmembers based on instances encountered individually, alone, one at a time. So far this is absolute, not relative. But on what basis do you categorize individual instances absolutely as members or nonmembers of the category, reliably and correctly? On the basis of whatever distinguishing features (called "invariants") will reliably resolve any confusion between members and nonmembers.

Now a nontrivial category will have (1) an infinite number of members and nonmembers (otherwise categorization would just be extensional: the rote memorization of all the finite members and nonmembers) and (2) the category's invariants will be underdetermined, i.e., hard to find, and possibly multiple and non-unique. How does the brain find the invariants of a nontrivial category that provide a sufficient basis for sorting instances correctly? 

A general mechanism is not yet known, but it is clear that (unless the category-detector is inborn, which simply raises the same question about evolution) it has to be found on the basis of trial-and-error learning through the sampling of members and nonmembers, guided by corrective feedback (in the form of adaptive and maladaptive consequences, in the case of evolved category-detectors), in order to somehow discover and extract or abstract the invariants that are sufficient for correct future sorting. Once you have found a reliable set of invariants, you have a category-detector, which is a kind of filter, applicable to new individual instances, and capable of correctly sorting them as members or nonmembers.

The categorization is still absolute, in that it is based on individual instances, encountered alone, not on pairwise or multiple comparisons. But it is relative in that it depends on the "context of alternatives" that have been sampled to date -- as well as on the empirical interconfusability among present and future instances that needs to be successfully resolved by the category-detector in order to generate error-free categorization. 

Because categorization here consists of a sensorimotor judgment by a categorizer, there is no guarantee that the category invariants will always work. Since we are not doing ontology here (even though this is a "metaphysics" thread), all we can say is that there is whatever there is in the world, and categorizers have whatever capacity they have to categorize some instances of those things correctly (in terms of the feedback from the adapative/maladaptive consequences of categorizing correctly and incorrectly), based on what sensorimotor (or symbolic) "input" instances they have sampled and what confusion-resolving invariants their category-detectors have successfully extracted therefrom. 

It is never certain that the context of alternatives sampled to date, on the basis of which the invariants were extracted, was a sufficiently representative and exhaustive sample to have provided a reliable basis for correctly categorizing all actual future instances, let alone all possible ones: +STRIPES and -LONG-NECK might be enough to sort zebras from giraffes for a lifetime on our planet, but they would no longer be enough if there were striped giraffes or long-necked zebras. (Some of this might be familiar to philosophers in the form of "grue" predicates and "twin-earth" and "category/schmategory" examples.)

So in that sense all category judgments and the category invariants on which they are based are relative to the context-of-alternatives sampled, rather than absolute: "How's yir woif?" "Compayured to whot?" This is just as true of the category BIRD as it is of the category BIG.

Harnad, S. (1987) Category Induction and Representation, Chapter 18 of: Harnad, S. (ed.) (1987) Categorical Perception: The Groundwork of Cognition. New York: Cambridge University Press. 
Harnad, S. (2005) To Cognize is to Categorize: Cognition is Categorization, in Lefebvre, C. and Cohen, H., Eds. Handbook of Categorization. Elsevier.  
Harnad, S. (2007) From Knowing How To Knowing That: Acquiring Categories By Word of Mouth. Presented at Kaziemierz Naturalized Epistemology Workshop (KNEW), Kaziemierz, Poland, 2 September 2007. 
Harnad, S; Blondin-Massé; A, St-Louis, B; Chicoisne, G; Gargouri, Y;&Picard, O.  (2008) Symbol Grounding, Turing Testing and Robot Talking.  RoadMap Workshop on Action and Language Integration, Rome on 22-24 September 2008.  

-- SH


2009-06-13
What is a relation?
Reply to David Bourget
On further reflection, I think the short answer to this question is that adicity refers to the number of roles in a relation, not the number of objects.  The same object can fill several roles.

Misconceptions also arise from focusing too fixedly on the elemental tuples of a relation instead of recognizing that the relation is a matter of what a whole set of tuples have in common.  This is true whether we take relations extensionally or intensionally.

Jon Awbrey