SUO: Metaphysics: a book report (long message)
Folks,
I thought I'd present a "book report" of Metaphysics by Michael Loux and
recommended on this list by Chris Partridge. I found this a very clear and
helpful book. I hope that its discussion of endurantism vs. perdurantism
will be enlightening since on this and several other topics, Loux outlines
the relevant arguments but does not, for the most part, take a particular
position.
INTRODUCTION
Loux explains metaphysics as
"...its aim is to identify the nature and structure of all there
is. Central to this project is the delineation of categories of being."
He also notes that
"...metaphysicians have disagreed about the categorical structure of reality."
An editorial comment that I would make is that any account of the world
must be consistent and stand up to scrutiny on the merits of its own
arguments, not simply because it is a widely held position. Nor do I think
we should be compelled to accept any one account in its entirety. We are
at liberty to create other accounts of the world and should choose them to
the extent that they provide greater descriptive power, even if they do not
accord with some previously held and labelled position.
I find the strongest arguments that Loux explains are those which
present examples or thought experiments that versions of the positions he
describes fail to capture adequately. Those examples or experiments
motivate modifications of the positions. Merely to say that "X who is a Y
won't accept this." is too weak an argument.
In Chapter Six Loux's Overview states that
"The endurantist claims that for a concrete particular to persist through
time is for it to exist wholly and completely at different times. The
perdurantist, by contrast, denies that it is possible for numerically one
and the same concrete particular to exist at different times...the concrete
particular is an aggregate ... made up of different temporal parts."
CHAPTER SIX
In the body of the chapter (my editorials within quoted passages are in []):
"...[Both theories assert that] concrete particulars [(instances)] are
entities with temporally bounded careers."
"...perdurantists insist that ... spatial parts and ... temporal parts are,
in one and the same sense, parts of a concrete particular. ...at any time I
am a spatial whole made up of spatial parts at that time, so am I a
temporal whole made up of all my temporal parts... [considerable elision]
...many of those parts overlap."
Loux then has some descriptions of the two positions which I find either
too difficult or more likely, take an account of a correspondence of the
positions with natural language rather than an account of the underlying
structures of the positions.
"Typical endurantists are what we might call presentists...only what exists
in the present really exists."
"Perdurantists [assert that] ... all times, all things existing at those
time...are equally real."
The former seems practically incoherent to me and can be addressed just by
a matter of modeling convention in which every statement is wrapped in an
implicit (holdsIn Now (...)) unless otherwise specified.
Loux also gives some nice analogies between 3d vs 4d as a debate similar to
possibilism vs actualism.
Loux goes on to discuss an odd position of some perdurantists that assert
that groups of entities that seems disconnected in a common sense view of
the world such as "Big Ben from ... noon to ... midnight...and Wmbley
stadium from 2pm to 3pm..." are just as real as the group "...the Loux of
yesterday and the Loux of today".
He continued to say "...Perdurantists insist that there are insupperable
logical difficulties in the assumption that we have numerical identity
where we have persistence through change." However this is unsupported.
Endurantists argue that the solution is to "...describe [a] ... situation
by time indexed properties..." Perdurantists them claim that endurantists
are committed to time indexing all properties. Endurantists reply that
they are not.
Perdurantists then argue that only their theory properly supports modeling
changes in parts of entities. This seems related however to another dogma
of Indiscernibility of Identicals (the notion that "if a is identical with
b then, for any property p, p is a property of a if and only if p is a
property of b") rather than a genuine criticism.
A stronger claim for a defect in the endurantist position is in the
following example. Say we have our friend Joe again and he loses an arm at
a point in time which we'll call "t". Endurantists acknowledge spatial
parts and so would allow the notion of a spatial part of Joe minus his arm,
so we have
JoeBeforeT, JoeAfterT, JoePartOtherThanHisArmBeforeT,
Before amputation we have both Joe and the part of Joe without his
arm. Endurantists also believe that Joe survives the loss of his arm with
his identity intact. After the amputation we have only a Joe without his
arm. This leaves us with the assertions that Joe is the same as both Joe
before the amputation as well as the more clearly true statement that Joe
after the amputation is the same as the spatial part of Joe minus his arm
before the amputation. Thanks to the Indiscernibility of Identicals
though, they can't both be true.
The Endurantist responds however in several ways
1. There are different notions of identity. One notion is strict and
requires all parts to be present. The other is informal. So the two
problematic statements are actually using incomparable identity
relations. This position is attributed to Roderick Chisholm
2. Peter Geach also asserts that there should be different notions of
identity but says instead of just two as in (1) that they should be with
respect to a particular class.
3. Peter Van Inwagen offers that there is no such thing as arbitrary
undetatched parts an so JoePartOtherThanHisArmBeforeT is not a legitimate
instance.
This is not the end of the argument since there are responses and
counter-responses to each of these points.
JOE'S ARM REVISITED
Let's consider an example again of Joe and his arm. Joe existed from the
year 1980 to 2000. So did his arm. Many aspects of Joe were
constant. Some were not.
Both 3d and 4d might assert the existence of Joe.
(instance Joe Human)
...and that he had an arm
(part Joe JoesArm)
A strict presentist would be unconcerned about the temporal characteristics
of Joe but would have no concrete objection to the inclusion of such
information other than an extreme adherence to Ockham's razor.
(start Joe Year1980) etc
It seems to me that the first concrete point of divergence in these
positions (with respect to practical modeling in a logical language) would
be once we want to talk about a change in properties of Joe during his
lifetime. For a perdurantist, properties are unchanging. An entity may
only have different spatio-temporal parts, each with different
properties. For an endurantist, properties of an entity may in fact
change. So, if Joe tragically loses his arm at age 10, the perdurantist
would state
(instance Joe Human)
(part Joe JoeFrom0to10)
(part Joe JoeFrom10to20)
(part JoeFrom0to10 JoesLeftArm)
(not
(exists (?X)
(instance ?X LeftArm)
(part JoeFrom10to20 ?X)))
whereas the endurantist would state
(instance Joe Human)
(holdsIn (IntervalFn (Year 1980) (Year 1990))
(part Joe JoesLeftArm)
(holdsIn (IntervalFn (Year 1990) (Year 2000))
(not
(exists (?X)
(instance ?X LeftArm)
(part Joe ?X))))
But why not simply allow both options when nothing prevents this other than
the dogma of each particular position? We only get into trouble when we
adopt the conventions of the perdurantist and expect endurantist notions of
identity to apply.