Ontology and phenomenology

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This paper is only an aside to the main body of work on the “Sense and nonsense in system theory” page.


Earlier papers have declared premises or business system modelling that include the following.

All behaviours in a system are performed by active objects that occupy space and must be addressable.

All regular behaviours in a system are triggered by discrete events, and run over time.


A business system model includes the names of these objects and events, and their attributes.

This is a domain-specific language, or ontology.

An ontology defines a set of representational primitives with which to model a domain of knowledge or discourse. 

The representational primitives are typically classes (or sets), attributes (or properties), and relationships (or relations among class members). 

[An aim] is to specify a data modeling representation at a level of abstraction above specific database designs (logical or physical), so that data can be exported, translated, queried, and unified across independently developed systems and services.



That all sounds rather “object-oriented”, but an ontology should cover events as well as objects.

All the activity systems we model are event processors; the system’s state advances event-by-event.

Events are the means by which a system recognises objects outside the system and detects changes in those objects.


An ontology specifies a vocabulary with which to make assertions, which may be inputs or outputs of knowledge agents (such as a software program). 

As an interface specification, the ontology provides a language for communicating with the agent. 

An agent supporting this interface is not required to use the terms of the ontology as an internal encoding of its knowledge.

Nonetheless, the definitions and formal constraints of the ontology do put restrictions on what can be meaningfully stated in this language. 

In essence, committing to an ontology (e.g. supporting an interface using the ontology's vocabulary) requires that statements that are asserted on inputs and outputs be logically consistent with the definitions and constraints of the ontology.



A system interface definition describes a system, it is a type that could be instantiated by several real-world systems.

If specifies events that enter the system and the system’s responses to those events.

Earlier papers suggested an interface hides the internal objects and structure of a system.

But it turns out some internal objects and structure do come to the surface - in defining the pre and post conditions of events.


Phenomenology is the study of a phenomenon through the senses rather than thought or intuition.

It is based on the premise that reality consists of objects and events ("phenomena") as they are perceived or understood in the human consciousness.


The papers on “Sense and nonsense in system theory” page are based on the notion that actors and systems are encapsulated within a wider world.

And they maintain a model of that external world.

They know the state of the world around them only in so far as they sense it through their interface.

The world exists right enough, but how it is modelled is entirely a construction of the system.

The model is judged to be accurate enough if the system survives or succeeds.



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