Thursday 6 August 2015

Against David Lewis's Intrinsic Properties

American philosopher David Lewis (1941–2001) wrote: “A thing has its intrinsic properties in virtue of the way that thing itself, and nothing else, is.”

[All the quotes from David Lewis come from his papers ‘Extrinsic Properties’ (1982) and ‘Redefining ‘intrinsic’’ (2001).]

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At first sight, the word “intrinsic” appears to be a virtual — or even literal — synonym of the word “essential”. Indeed it’s tempting to use the latter — rather than former — word. However, as often happens in analytic philosophy, there are indeed (slight?) differences between these two ontological categories. Or, at the very least, there are different definitions of the words “intrinsic property” and “essential property”. Nonetheless, it can still be said that the two categories are very-closely related. To put that another way: this (possibly) insubstantial or even empty (to use Derrida’s term) “sign-substitution” of “intrinsic” for “essential” would never have happened if essentialism and anti-essentialism had never been such important parts of the Western philosophical tradition.

In any case, some metaphysicians tell us that there’s a difference between properties which object O has independently of any external factors acting upon it (i.e., intrinsic properties) and O’s properties which are deemed to be the way they regardless of what’s external to it (i.e., essential properties). Despite saying that, can’t that account of intrinsic properties also be applied to essential properties? In addition, can’t we also say that essential properties are those properties which are independent of any — or all — external factors?

If all that’s the case, then what has happened here isn’t the discovery of another ontological category: it’s a new way of accounting for an old ontological category. That is, when essential properties are defined in such a way as to emphasise their independence from all external factors, then those properties become intrinsic in nature — even though they’re essentially the same as essential properties! Again, the only things that seems to have changed are the new technical terms and their definitions.

David Lewis on Intrinsic Properties

This is David Lewis’s own definition of intrinsic properties from 1982:

“A thing has its intrinsic properties in virtue of the way that thing itself, and nothing else, is.”

Could there ever be such a state as “the way that a thing itself []is” regardless of literally everything else? That is, regardless of its (actual, not possible) relations to properties/objects, events, conditions, etc. which are (as it were) outside itself; as well as regardless of its place in time and space?

This position can be taken to its most extreme (or perhaps ridiculous) in the following statement:

Object O would still have intrinsic property P if after the world around it disappeared, O would still have P.

(This is a little like Max Black’s two-sphere universe; as discussed in his paper ‘The Identity of Indiscernibles of 1952.)

Can we say that there are intrinsic properties which still have vital (or important) relations to extrinsic properties? Alternatively: object O’s extrinsic proprieties may determine — to some extent at least —its intrinsic properties. However, it may be countered that because objects are such-and-such-a-way, then they can only be determined (or affected) in particular ways precisely because they have the intrinsic properties which they do have. So that may mean that there are mutual relations between intrinsic and extrinsic properties. Indeed, as just stated, there may not even be a “way” an object is regardless of its relations to other things or to extrinsic properties.

David Lewis also cited “internal structure” as being intrinsic to objects. Yet if such a structure is defined in terms of its relations, then surely it must also be defined (at least partly) in terms of extrinsic properties. This would mean that Lewis’s internal structure would also be defined — or even constituted — by its relations to extrinsic properties.

That would also mean that internal structures determine an object’s relations and therefore also determine the extrinsic properties themselves. Then again, it can also be argued that external properties determine internal structures.

Here again the boundaries between what is intrinsic and what is extrinsic seems to be somewhat blurred.

Of course it can now be asked what would be the metaphysical point of a Lewisian internal structure if it weren’t primarily a crutch (or framework) for intrinsic properties which have no such relations at all to external properties.

Different Surroundings and Shape

David Lewis claimed something about an intrinsic property which isn’t entirely helpful unless one’s already sure what a property actually is. He wrote:

[] If something has an intrinsic property, then so does any perfect duplicate of that thing; whereas duplicates situated in different surroundings will differ in their extrinsic properties.”

The problem with that definition (a mere stipulative definition?) is that if the very same “thing” is in “different surroundings”, then it may also have different intrinsic properties to the ones it had in its previous surroundings (what Lewis called “temporary intrinsics”). To put that more clearly:

1) Object O has set of intrinsic properties I¹ in surrounding S.
2) Object O has set of intrinsic properties I² in surrounding S².

To put that in more basic words: object O may change its intrinsic properties (not only its extrinsic properties) in different places. And that, surely, will depend on its relations to other objects; as well its relations to (external) properties.

Lewis also argued that the shapes of objects are intrinsic to such objects. However, don’t the shapes of many — or all — objects change through time?

One (as it were) shape-changer is space itself.

More correctly, objects with mass (at least to some minute degree in many cases ) curve spacetime and spacetime shapes objects. Thus shape will depend on the curvature of space in a specific region. What’s more, the curvature of space will be continuously working as a shape-changer.

But what if spacetime never has an impact on the shape of (as J.L. Austin put it) “medium-sized dry goods”? That said, the curvature of space does indeed have an impact on how such objects travel through space (as well as vice versa); though even here the impact is minuscule. (Massive objects, such as the earth, are a different matter.)

So what about particles and other micro-phenomena? Is it the case that the curvature of space doesn’t have any impact at the quantum level? (This ties in with the issue of quantum gravity.)

In any case, what if object 0’s shape at time t¹ is intrinsic and object O’s (slightly different) shape at t² is also intrinsic to it? However, if O’s shape were always changing, at least one of its intrinsic properties would also be changing. That’s because it would have two supposedly intrinsic shapes at two different times. And that seems to go against the notion of intrinsicality.

Intrinsic Relations

An interesting addition to the notion of intrinsic properties would be the category of intrinsic relations.

Intrinsic relations are said to determine — or even constitute — the nature of objects. In other words, they’re fundamental (why not say essential?) to the objects which have them.

This is primarily the case because it can be argued that object O’s intrinsic relations to other objects (or set/s of properties) are actually constitutive of what O actually is. So aren’t an object’s relations constitutive — or part — of that object’s fundamental (or essential) nature?

For example, the property [being two miles away from] can be deemed to be an intrinsic relation between two objects. Similarly, the property [being the same species as] can be seen that way too.

Clearly, if object O is two miles away from another object, then that other object must also be two miles away from O. So, in this case at least, the property [two miles away from] is symmetrical in regards to O and that other object.

Similarly with the property [being the same species as]. If object O is the same species as another object, then that other object must be the same species as O.

So can relational properties really be deemed to be intrinsic?

It may seem counterintuitive (to some) to argue that the relation [being two miles away from] could be an intrinsic property of object O. Indeed can it even be any kind of property at all?…

What about the property [being the same species as]?

Surely in the case of object O we can say that its being a member of species S is intrinsic. However, why should we say the same about the property [being the same species as] itself? That seems to be a needless addition to one’s ontology.

In any case, it can be argued that a pair of subatomic particles can display (or partake of) intrinsic relations.

For example, say that electron a and proton b (always?) stand in relation R to one another. Thus:

R is an intrinsic relation between a and b iff a (always) stands in R to b and b (always) stands in R to a.

That relation will also determine the natures of both a and b. In fact it can be argued that the intrinsic relation (or mutual relations) is (or are) actually constitutive of the natures of both a and b.

Electron a and proton b (or any other pair of objects), on the other hand, may also be related to all sorts of other objects, properties or events which don’t help constitute their fundamental natures or intrinsic properties.

In ontic structural realism, for example, this category of intrinsic relations is certainly taken to be true of subatomic particles (though ontic structural realists neither use that term nor accept it). Yet, perhaps ironically, this leads ontic structural realists to deny that there are any (only?) subatomic “things” at all (i.e., as in “every thing must go”).

So could all this be applied to macro-objects such as persons or trees too?

And need we follow the ontic structural realists in denying that there are things (or objects) simply because they always have (fundamental?) relations to — or indeed are partly constituted by — other objects, events, external properties, etc?

Lewis also mentioned a “perfect duplicate”.

Duplicates?

According to Lewis, if there were a perfect duplicate of Davy Boy, then that duplicate and Davy Boy would share the same intrinsic properties.

This means that the idea of a perfect duplicate sharing all intrinsic properties is helpful for a possible-worlds theory in which counterparts share such intrinsic properties. Thus:

If objects a and b are duplicates, then they must share all their intrinsic properties (i.e., even if they have different extrinsic properties).

It’s also argued that objects and even persons must have intrinsic properties in order to exist — over time — as the objects and persons that they are. In other words, if there were no intrinsic properties, then a given object or person would only last for a second… or even less… and would therefore not be a object or person at all.

What’s more, if there were a duplicate of Davy Boy, wouldn’t that duplicate also share all his extrinsic properties? To put that more simply: wouldn’t he (or it) share all his properties by virtue of him (or it) being a duplicate? After all, on Lewis’s picture, counterparts only duplicate the intrinsic (or essential) properties of the objects they’re counterparts of.

Yet wouldn’t all that be to simply assume certain things?

Counterpart theory is (in part) used to distinguish intrinsic from extrinsic properties. However, in order to have duplicates one must already be committed to intrinsic properties in order to define — or even understand — what it is that’s being duplicated. So rather than discovering intrinsic properties through counterpart (or duplicate) theory, one must actually assume them. Moreover, not only is the existence (or reality) of intrinsic properties assumed, so is what is and what isn’t an intrinsic property.

To sum up some of the above in argument form:

i) If object O changes its intrinsic properties in (to use Lewis’s words) “different surroundings”
ii) then any distinction between intrinsic and extrinsic properties (at least in the case of
O) will be difficult (or even impossible) to make.
iii) Therefore get rid of the distinction between intrinsic & extrinsic properties entirely.

There’s an additional way of looking at conclusion iii) above. Thus:

i) If the intrinsic/extrinsic distinction fails for objects (or Lewis’s things),
ii) and the having of intrinsic properties is said to be fundamental for the
discernibility, individuation, etc. of objects,
iii) then the ontological reality of objects itself may be questioned.

Surely the conclusion to all this is that it’s very hard to distinguish intrinsic from extrinsic properties. And, if that’s the case, then why not give up on the distinction altogether?


(*) See also: ‘Rearrangement of Particles: Reply to Lowe’ (1988)




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