Domain Theory

Roberto Poli

Domains—Domains—Domains We need domain theory for the same reasons science is

developed into different branches: Reality is too complex to be understood ‘at a stroke’

The only way we have found to develop our understanding of reality is to fragment it into separate parts (our domains) and to proceed by analyzing one part at a time

The guiding idea Segment the whole of reality into classes of connected

phenomena Phenomena occurring within each class are more homogeneous

than are phenomena pertaining to other classes, so that the task of explaining their behavior should be more easily accomplished

Domain theory cannot be limited to science, however Many domains are only remotely, if at all, connected to science

(common sense, behavioral practices, aesthetic experiences, etc)

Questions about Types of Domains Are there different types of domain? How many different types should be distinguished? What is their internal organization? How are the different types related to each other? Is there any methodology which helps to establish a

domain’s boundaries?

Domains Sharply defined domains with well-defined boundaries Blurred domains, depending on highly pragmatic

decisions/interests Many domains present intermediate values between these

two cases Underdeveloped state of the theory of domain

Domain Types of domain

Domain in the proper sense (e.g. biology) Sub-domain or facet frameworks (e.g. genetics) Cross-domain (e.g. medicine) Micro-domain (e.g. edible substances)

I shall presented the first two types in some detail

Main difference between domains in the proper sense (first case) and all the other cases. This explains why finding a criterion with which to distinguish proper domains from the other domain-types is mandatory

The Framework

Levels of Reality

Domain Theory

Wholes

Levels of reality distinguish types of entities (material, psychological, social entities)

Wholes distinguish types of structures (aggregate, system)

A level of reality usually requires a vast array of cate-gories. I would like to see whether domains can be organized around some basic types of entities

A Proposal Domain1 = Categorically closed, maximal partition of

reality

Categorically closed = even if the domain’s entities may be existentially dependent on lower and/or adjacent entities, they nevertheless require a categorical framework different from the one used to understand the entities of the existentially supporting levels Organisms require chemical entities (molecules) which require

physical entities (atoms) as their ‘matter’. However, the frameworks needed to understand biology, chemistry and physics are different

Maximal partition of reality = the domain includes all the entities that are selected by its categorical framework

Whatever the merits of this proposal, it entails that not any partition whatsoever is a domain (in the proper sense)

From Levels to Domains Hypothesis: For any domain, some of its

entities are more characterizing than others Biology (simplified)

Biological entity (BE) Living entity (LE) Organism (OR)

Biological Entity (BE) BEs delimit the field of biology BEs include biological items such as the nucleus of a

cell, the membrane of a cell, its organelles, DNA, mRNA, and urine. None of these is a properly living entity: they pertain to parts of a living entity or to their products or waste (urine)

BEs also include non-biological items such as the nests made by birds and the pebbles eaten by chickens. Some nests are made of twigs and other matter; others are f.i. deliberately made holes in the ground. Holes and pebbles are not ‘biological’ entities in any proper sense of the term. They pertain, however, to the field of biology, because they are constructed by authentically biological entities (organisms) or are needed by them. We can consider them as entities with a primary physical nature and a secondary biological one

Living entities (LE) LEs constitute a specific class of BEs. All LEs

are systems, while not all BEs are. Furthermore, LEs are metabolic systems, i.e. LEs are entities that can survive if appropriate nutrients are provided. Cells, tissues and organs are cases in point.

Organisms (OR) ORs are autopoietic LEs, i.e. LEs able to produce the

BEs of which they are composed. Two main types of ORs should be distinguished: unicellular and multicellular The distinction between unicellular and multicellular

entities requires to articulated along the customary distinction between prokaryotes and eukaryotes. The former are unicellular entities whose genome is not enclosed within the cell’s nucleus, while the latter can be either unicellular or multicellular and are such that their genome is enclosed within the cell’s nucleus

A cell which is a unicellular organism is a BE, a LE and an OR. A multicellular organism as a whole is a BE, a LE and an OR. However, the cells of multicellular organisms are living entities but they are not organisms (a liver cell is a living entity but not an organism)

Caveat! If one subtracts LEs from the field of the biological

BEs, what remains coincides with the field of organic chemistry. This shows the link between biology and its underlining level of reality

However, there are differences. The subtraction of living entities modifies the situation in such a way that a number of questions become unanswerable. Even if urine is a purely chemical substance (well, a mixture of substances), how can one explains its presence without taking organisms and their metabolism into consideration?

The questions asked from within organic chemistry and those asked from within biology are different. This shows that they are different domains. The reason for their difference lies in the entities grounding their specific levels of reality: molecules for chemistry and cells for biology

Facets The next step after establishing the core

categories is to determine the dimensions of analysis of the domain’s entities. This is where facet analysis comes in

With reference to the domain of biology, two series of facets follow The first series lists the characteristics from which

an organism as an actually given object-type can be seen.

The second series of facets lists all the other characteristics, those not focused on the organism as an actually given object-type

Facets, first series The first series is centred on the governing concept of organism as

an individual whole and lists the “viewpoints” from which organisms as an actually given object can be seen. One can then consider at least the following four cases: Classification (Taxa), Structure, Function, Behavior

Classification models biological taxonomies Structure applies part-whole analysis to cells and organisms, for

both parts, organs and tissues. Traditionally this type of analysis is called cytology for cells and anatomy for multicellular organisms

Function corresponds to what is traditionally called physiology and model the working of the part descriptively listed by the previous facet of the organism’ structure. In the case of the facet of functions, (serious) variations are usually called pathologies (to be further distinct between intra- and inter-systemic pathologies)

Behavior deals with the organism’s actions. It requires consideration of the organism’s environment (ethology)

Facets, second series The second series of facets list all the other

viewpoints, those not focused on the organism as an actually given object

Two main cases derive Facets focussed on the organism as a whole. These

may include the growth, development and reproduction of organisms

Analysis of the various parts of this whole, e.g. the genes governing the production of the organism

Facets, again Objects pertaining to different domains may

require different facets Establishing a universal list of facets will guide

analysis and help in maintaining greater methodological coherence across domains

Facets—facets—facets By comparing and integrating the ancient

Aristotelian list of categories with the list produced by the Classification Research Group, one obtains a 16-entry list

A 16-dimension analysis, however, is both difficult to manage and cumbersome from a cognitive point of view

Grouping the 16 dimensions into some groups provides an environment easier to understand and manage, and helps in adding consistency controls

The Table of Facets

Item Analysis Process ContextSpacetim

e

NameKind

(hyperonym)

Internal prContext

(related to)Space

Ambit(type of)

Operation Time

Structure Patient

Property Function

Matter Outcome

By-product

Agent

Comments

Unbalanced groups of categories Relevance of the group of processes Context underrepresented (may depend on

not having discussed ‘wholes’) Entries of the groups ‘analysis’ and ‘process’

are mutually connected

Item Analysis Process ContextSpacetim

e

Name Kind Internal pr Context Space

Ambit Operation Time

Structure Patient

Property Function

Matter Outcome

By-product

Agent

Levels of Reality

Domain Theory

Wholes