A DATABASE SEMANTICS
F. NATURAL VS 'SOCIAL KINDS IN ORGANIZATIONAL VOCABULARY 15
Chapter 4
A REFERENCE
I t is not only with respect to databases that one can find &ssatisfac- tion with model theoretic semantics. There is also a movement within analytic philosophy to bring these semantic theories more into accord with the mundane mechanisms of language use. ' R u s movement focuses particularly on aspects of r e f m m c e , how a symbol is l~nked to its denota- tion. Tlus pertains both to the naming of individuals and the naming of classes.
Of particular interest here are the categories we use for our every- day objects, so-called nutural kinds, such as lemon, bottle, chair. When examined through the pe~spective of model theoretic semantics described in the last chapter, the existence of such kinds is p u z z h g . Thls puzzlement arise; largely as a result of adopting set theory as the principle device for explain~ng how real world objects are organized.
The problem is essentially that any collection of objects can consti- tute a set
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e.g., the set consisting of my toothbrush, the Eiffell Tower, and the planet Saturn. Given all the possible sets of things, why are some, e.g., lemons, chairs, given a special status and assigned a name?The problem becomes all the more complicated if the dimensions of time and possible worlds are added. (E.g.. an arbitrary set m g h t then include hypothetical individuals such as Abraham h c o l n ' s automobile, the present Kmg of France and the city of Atlantis).
An early reply to this problem was that natural kmds were sets defined intensionally. That is, there were certain 'critical properties' that selected the members of these sets. An obvious problem with thls view is
- 3 - Chapter 4 that, from the standpoint of model theoretic semantics, this involves a circular. argument: One cannot explain properties by their set denota- tions and then turn around and explain the sets denoted by their inten- sional properties. However, this merely casts doubt on the denotational approach to semantics and suggests that perhaps intensions should be taken as primary after all.
However, the criterial properties approach also quickly runs into dif- ficulties. Consider the concept of a chair. What a r e its criterial proper- ties?
a. that it has four legs? No, there are chairs without four legs.
b. that it has a horizontal surface and a vertical back? No, for instance a bean bag chair has neither of these.
c. that it is somet-. to sit on? We can sit on many t-s that aren't chairs.
'Rm view is conjunctive
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it requires that each element of the intended set satisfy the several criterial properties simultaneously.An alternative view is disjunctive: that there are no single properties that r u n throughout the s e t of thmgs we call chairs, but it is rather the disjunction of several properties that define this set. For example, a chair is:
four-legged o r
has vertical and horizontal surfaces, or is used to sit on, etc.
- 4 - Chapter 4 The problem here is that it tends to include too many things -e.g., tables would count as c h r s by t b s definition. Wittgenstein (1953/1958) is a classic philosophical discussion of the shortcomings of the criteria1 pro- perties (or essentialist) view of semantics.
More recently, attempts have been made to get around this problem by saying that the denotation of natural kind types of predicates is a fuzzy set. Without debating the adequacy of fuzzy set theory, we observe merely that t b s misses the basic point. The problem is not whether the boundaries of these sets are sharp or fuzzy, but rather why they are selected and named in the first place.
Providing more pragmahc motivations for these sorts of semantic issues, Kent (1978) cites numerous examples arising in data processing applications. Far exampie, consider the natural kind, street:
What is one street? Sometimes the name changes; that is, dif- ferent segments alodg the same straight path have different names. Based on a comparison of addresses, we would probably surmise that people on those various segments lived on different streets. On the other hand, different streets in the same town may have the same name. Now what does an address com- parison imply?
Sometimes a street is made up of discontinuous segments, perhaps because intervening sections just haven't been built yet. They may not even be on a straight h e , because the ulti-
Chapter 4 theory of reference'.
The discussion in this chapter will therefore focus initially on indivi- duals and the epistemic aspects of proper names. Buildmg on that, the recognition and narnlng of natural kinds is considered. These depend on social conventions that, particularly for economic goods, change over time. Social movements and economic innovation are reflected in h g u i s - tic changes. Organizational adaptation likewise depends on linguistic evolvability. Structured information systems, relying on a fixed, stable semantics, constrain this evolution.
In the last chapter, ontology was discussed as the choice of the domain of individuals, D. The elements of this set are called simply indivi- duals. In database management, the term 'entity' is more frequently used, but this has the drawback that it tends toward a certain contusion between a particular entity or the generic class (e.g., EMPLOYEE a s an entity).
Understanding natural kinds, it turns out, depends on understandmg the conventions for recognizing and naming the individual entities included in the land. The recognition of a single individual is called indi- M i o n . This has a static and dynamic aspect: recognizing the indivi- dual a t a point in time, and recognizing that individual as it undergoes change. The importance of individuation is that i t is the criteria by which we assign names or identiiiers to an individual. To use a name (in a for- mal language or a database) presupposes that all of the users of the language/database agree on the object desgnated by that name. Thus,
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the problem of individuation has its dual in the problem of sameness. If a and b are names, a = b asserts that these name the same object*
A thorough study of the various aspects of individuation is Strawson (1959). He claims that our basic criteria for individuation is the object's location in a spatial/temporal framework. Hence, the objects easiest to individuate with reasonable consensus are e.g.. physical objects and events somehow related to physical objects. 'Rus is a very important observation since it gives us some insight into areas where individuation is likely to be difficult, namely abstract objects not involvmg space/time locatability
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Consider for example Beethoven's 5th Symphony. What is the deslg- nation of this term? Is it the event of Beethoven's composing t h s piece?
Is it the paper it was 01-lginally written on? Is it the collection of all paper reproductions, etc. of this original? I s it .a musical performance of this piece? Is it all musical performances, past and future of t h s piece? We would like to say that it is none of these. Beethoven's 5th Symphony is an idea, and these examples are all mere conveyances of this idea.
A more modern example, coming into increasing economic impor t a m e is the individuation of computer programs. Like the symphony, computer programs have static representations on disk, in core, etc. as well as performances - i n the execution of the program. Yet, again we would like to claim that the computer program is actually an idea.
Two samenesr problems are sometimes -uished: sameness of individuals w sameness of kind. For example, "John and Bill drive the same cai' may mean they drive the same par- kcular car, or that they each drive distinct cars that are of the same type (satisfy the s a m e predioates). Lnsofar as the extension of a predicate is a set of individuals, sameness of kind also relies on individuation.
- 7 - Chapter 4 Consider the problem of software theft. Typically when something is stolen, the owner suffers its loss. In the case of stolen software, however, the owner often can't even detect the loss. Theft is probably the wrong word here -it is actually more Like plagiarism. However, the point is the same: if we want to talk about particular symphonies or computer pro- grams, it i s very hard to do so without relating them somehow to a spatio-temporal framework.