New directions for ontology design in history and archaeology Khazraee & Lin Version 1 New directions for ontology design in history and archaeology Introduction: Historical and archaeological data is very diverse and dispersed in different institutions even in different countries. Moreover, the pace of data production in this field is far more than data processing. Data processing usually leads to archaeological reports and sometimes to historical narratives about the subject of the study. The imbalance between data production/collection and data process in many cases reaches decades; therefore, many of the people involved in the projects would not be available anymore. That is why there are inventories in museums belong to decades ago which have not been studied yet. In most scientific fields, the obstacle of time consuming calculations and data processing have been reduced dramatically in the last decades due to cheap computation power. A precondition to benefit from machine power is to convert data to computable format and to formalize data processing into machine processable formats. This task, more or less, would be possible in those domains of knowledge which have explicit terminology, well-formed definitions, generic forms of analyses and techniques for verification. However, history is different from sciences as it lacks three following properties, established specific terminology, stipulated meaning for lexical elements, and explicit rules of inference (White, 1973b). Moreover, uncertainty, contradictory data, and validity of different perspectives are intrinsic characteristics of historical investigation; thus, these make historical reasoning process more complex. Consequently, the result is the slow pace of data processing in comparison to data production. Page 1 of 19 New directions for ontology design in history and archaeology Khazraee & Lin Version 1 Ontologies are known as artifacts designed to model domains of knowledge in a machine understandable manner (Gruber, 2009). Ontologies used to improve the shared understanding of people and software agents and enable automatic/semi-automatic knowledge acquisition and reasoning. In many cases it is indicated that ontologies are silver bullets of knowledge management or Semantic Web (Fensel, 2004). However, these promises seem optimistic, in order to exploit machine power in historical data processing it would be necessary to achieve machine interpretable knowledge (Poole, Smyth, & Sharma, 2009) which is tied with knowledge representation and ontologies. It would be obvious that ontology design practices in the scientific domains are not completely applicable for the domain of history. Without clear understanding of the nature of a domain of knowledge it is not possible to design systems to represent or model that domain. Therefore, it would be necessary to inquiry the epistemological assumptions and methods of investigation in that domain of knowledge. This paper proposes to use domain analysis as a paradigm in information science to address the considerations of ontology design in history and archaeology. Domain analysis is a paradigm in Information Science (IS) which recognizes the study of the knowledge-domains as the best way to understand the requirements of information (Hjørland & Albrechtsen, 1995). This study considers cultural, historical, and social aspects of a domain of knowledge (Hjørland, 2002). To find the fitness of any knowledge organization method, domain analysis proposes, to study the domain itself, and to explore its different aspects as follows: Ontological aspects (objects of human activity within a domain), epistemological aspects (the process of obtaining Page 2 of 19 New directions for ontology design in history and archaeology Khazraee & Lin Version 1 knowledge and investigating in a domain), as well as sociological aspects (those groups of the people and institutions dealing with mentioned objects) (Hjorland & Hartel, 2003). This paper first reviews different notions of ontology. Next complexities of ontologies for history and archeaology will be studied and finally, new directions for ontology research in history and archaeology will be presented. What is ontology? The term ontology has a long history in philosophy. This term is known as the synonym of metaphysics (which means what comes after physics), and developed as a discipline by Aristotle who used the term “first philosophy” instead (Smith, 2003). The word ontology comes from the Greek ontos and logos stand for being and word (Sowa, 2000). Smith (2003) traced the first use of the term in early 17th century by two philosophers, Jacob Lorhard and Rudolf Göckel, and he added that the first appearance in English dated back to 1721, in Bailey's dictionary. Later, the term “formal ontology” was first used by Husserl in logical investigation (Smith, 1989). The term “ontology” has been being used in computer and information science community since 1980's and during this period different notions have been proliferated around this term. We should differentiate between ontology as a discipline and ontology as an artifact*. The main concern in Ontology as a discipline in philosophy is to answer the question of “what exists?” Therefore, it is a methodological study of the account of existence. “Philosophical ontology is the science of what is, of the kinds and structures of objects, properties, events, processes and relations in every area of reality”. Ontology in * To disambiguate these situation, “Ontology” with uppercase “O” will be used for ontology as a discipline and the term “ontology” with lowercase “o” will be used for ontology as an artifact. Page 3 of 19 New directions for ontology design in history and archaeology Khazraee & Lin Version 1 philosophy looked for “definitive and exhaustive classifications of entities in all spheres of being” (Smith & Welty, 2001, p. i). On the other hand, ontology as an artifact is “a technical term that is designed for a purpose, which is to enable the modeling of knowledge about some domain, real or imagined” (Gruber, 2009). Legg (2008) argues that “kinds and structures” in Ontology are called categories and this terminology carried over the term ontology in information science. Smith (2003) explains that the motivation behind the ontology in computer and information science is to resolve terminological and conceptual conflicts; therefore, it is seen as a shared taxonomy of entities. He also recognizes a more ambitious definition for ontology in this context as a formal theory which includes both definitions and supporting framework of axioms (Smith, 2003). The former distinction between Ontology (as discipline) and ontology (as a knowledge artifact) is the most radical distinction among different usages of the term. The other differences are more subtle than the former. In mid 90's Gruber provided the mostly accepted definition of the term ontology as, “a formal specification of a conceptualization” (Gruber, 1993). One of the reasons that this definition is widely accepted in the three mentioned community, is its generality. Thus, each community can use it for their own purpose. The most general interpretation of Gruber's definition claims that ontology is a list of existing concepts or entities in a domain. These set of terms or vocabulary can be structured in the form of a hierarchy or a lattice. Soergel (1999) believes that ontology is a new brand invented to be used instead of classification. More sophisticated interpretations do not accept this approach and put emphasis on the formal Page 4 of 19 New directions for ontology design in history and archaeology Khazraee & Lin Version 1 aspect of an ontology. In this sense, an ontology is a structure which is expressed in a formal language and can be shared among different agents. This interpretation forms a spectrum of artifacts which is known as the ontology spectrum (Uschold & Gruninger, 1996). At one end of the ontology spectrum, there are lightweight structures with minimal semantics and formality and at the other end there are structures with richer semantics and formality. This spectrum has been mentioned in different works of the researchers in the domain (McGuinness, 2003; Smith & Welty, 2001; Guarino, Oberle, & Staab, 2009). Although, different authors mention this spectrum of ontologies but each of them emphasizes a specific type of ontology as their choice. Noy and McGuinness (2002) define an ontology as a machine-interpretable common vocabulary which is used to share information about a domain. Uschold and Gruninger (1996) define ontologies as “the shared understanding of some domain of interest which may be used as unifying framework” (Uschold & Gruninger, 1996, pp. 96-97). Later they used Gruber's definition as the standard definition of ontology indicating that the main difference among the approaches to ontology is in the level of specification of the meaning of the terms used in the ontology. They show that there is a continuum starts with little specification of the meaning and ends with rigorously formalized theories (Uschold & Gruninger, 2004). Guarino et. al. (2009) provide a more detailed definition of the ontology by explicating the important aspects of the definition of ontology as “a formal, explicit specification of a shared conceptualization” (Guarino et al., 2009, p. 2). They differentiate among conceptualization as a structure of intensional relationships and a structure of extensional Page 5 of 19 New directions for ontology design in history and archaeology