OpenHPI 4.1 - Ontologies as Central Concept in Philosophy

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OpenHPI 4.1 - Ontologies as Central Concept in Philosophy

  1. 1. Semantic Web TechnologiesLecture 4: Knowledge Representations I01: Ontology as Central Concept in Philosophy Dr. Harald Sack Hasso Plattner Institute for IT Systems Engineering University of Potsdam Spring 2013 This file is licensed under the Creative Commons Attribution-NonCommercial 3.0 (CC BY-NC 3.0)
  2. 2. 2 Lecture 4: Knowledge Representations I Open HPI - Course: Semantic Web Technologies Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  3. 3. 3 01 Ontology as Central Concept in PhilosophyOpen HPI - Course: SemanticHarald Sack, Hasso-Plattner-Institut, Universität Potsdam Semantic Web Technologies , Dr. Web Technologies - Lecture 4: Knowledge Representations I
  4. 4. 4 „People can‘t share knowledge if they don‘t speak a common language“ Thomas Davenport (1997) Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam Turmbau zu Babel, Pieter Brueghel, 1563
  5. 5. Sharing Knowledge5 To speak a common language... • common symbols and concepts (Syntax) • agreement about their meaning (Semantics) • classification of concepts (Taxonomy) • associations and relations of concepts (Thesauri) • rules and knowledge about which relations are allowed and make sense (Ontologies) Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam Turmbau zu Babel, Pieter Brueghel, 1563
  6. 6. What is Knowledge?6 Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  7. 7. What is Knowledge?6 Truths Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  8. 8. What is Knowledge?6 Truths Beliefs Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  9. 9. What is Knowledge?6 Truths Beliefs Knowledge Traditional Definition: „Knowledge is a subset of all true beliefs“ Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  10. 10. 7 To represent knowledge, we need a formal knowledge representation: Ontologies Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam Turmbau zu Babel, Pieter Brueghel, 1563
  11. 11. Definition • ον [greek] participle of „to be“ λογια [greek] science8 „philosophical study of the nature of being, existence, or reality, as well as the basic categories of being and their relations....“ (wikipedia) • „what does exist or can be said to exist?“ General Metaphysics ⇳ Epistemology Raffael: Die Schule von Athen, 1510-11 Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, UniversitätChristian Wolff: Philosophia prima sive Ontologia, 1729 Potsdam
  12. 12. Fundamental Questions of Ontology 1.What does it mean for a being to be?9 • When are two things identical? • Is everything that exists also real? • Does something exist, if it is only possible? • Are there non-existing things? Jacob Lorhard: Ogdoas Scholastica, continens Diagraphen Typicam artium: Grammatices (Latinae, Graecae), Logices, Rhetorices, Astronomices, Ethices, Semantic Web Technologies , Dr. Harald Sack, Physices, Metaphysices, seu Ontologiae. Sangalli: Straub, 1606 Hasso-Plattner-Institut, Universität Potsdam
  13. 13. Fundamental Questions of Ontology 1.What does it mean for a being to be?9 • When are two things identical? • Is everything that exists also real? • Does something exist, if it is only possible? • Are there non-existing things? 2.What categories of objects do exist? • Do things exist that are only unique or only multiple (Universalia)? • Do things exist that are unilaterally dependent of others (Substances)? • Of which sort is this dependency (Causality)? • Do necessary properties exist (Essences)? • How do composed things relate to their components? Jacob Lorhard: Ogdoas Scholastica, continens Diagraphen Typicam artium: Grammatices (Latinae, Graecae), Logices, Rhetorices, Astronomices, Ethices, Semantic Web Technologies , Dr. Harald Sack, Physices, Metaphysices, seu Ontologiae. Sangalli: Straub, 1606 Hasso-Plattner-Institut, Universität Potsdam
  14. 14. Ontology: where does the term come from?1610 • „Ontology“ first turned up in 1606 („ontologia“ in Latin) by Jacob Lorhard in his book „Ogdoas Scholastica“ • In German language the term „Ontologie“ first turns up in 1613 in Rudolf Göckel‘s „Lexicon philosophicum“ Rudolf Goclenius the Elder (1547-1628) Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  15. 15. Ontology: where does the term come from?1611 • Christian Wolff named Ontology Ontologya philosophical disciplinespecific in of Metaphysics, more as Part Classic Greek Philosophy of general metaphysics (metaphysica generalis) • Traditional Ontology deals with the relation of the ,being‘ to „existence“ • ontological difference (Heidegger) • Division of „Existenciality“ and Christian Wolff „Categoriality“ (1679-1754) Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  16. 16. Ontology in Classical Greek Philosophy1612 • Fundamental Question: „What are the fundamental categories of existence?“ Parmenides (ca. 535-470 BC) Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam Raffael: Die Schule von Athen, 1510-11
  17. 17. Platon (427-347 BC) Ontology in Classical Greek Philosophy1613 sensory Rational/Mind perception recollection (empeiria) (anamnesis) ideas objects imutable mutable imperishable perishable Archetypal Image acc. to http://upload.wikimedia.org/wikipedia/commons/7/7d/Platon_Ideenlehre.svg Socrates Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam (469-399 BC)
  18. 18. Aristotle (384-322 BC) Ontology in Classical Greek Philosophy1614 • Aristotle (Metaphysics IV, 1) defines a system of general categories for classification of all things about which statements can be made Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  19. 19. Aristotle(384-322 BC) Ontology in Classical Greek Philosophy1615 Syllogisms • συλ-λογισμός [griech.] add up, logical conclusion • Core of Aristotelian logic • Inference rules, all built according to the same pattern Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  20. 20. Aristotle(384-322 BC) Ontology in Classical Greek Philosophy1615 Syllogisms • συλ-λογισμός [griech.] add up, logical conclusion • Core of Aristotelian logic • Inference rules, all built according to the same pattern major premise All humans are mortal Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  21. 21. Aristotle(384-322 BC) Ontology in Classical Greek Philosophy1615 Syllogisms • συλ-λογισμός [griech.] add up, logical conclusion • Core of Aristotelian logic • Inference rules, all built according to the same pattern major premise All humans are mortal minor premise All Greeks are humans Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  22. 22. Aristotle(384-322 BC) Ontology in Classical Greek Philosophy1615 Syllogisms • συλ-λογισμός [griech.] add up, logical conclusion • Core of Aristotelian logic • Inference rules, all built according to the same pattern major premise All humans are mortal minor premise All Greeks are humans conclusion All Greeks are mortal Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  23. 23. Aristotle(384-322 BC) Ontology in Classical Greek Philosophy1615 Syllogisms • συλ-λογισμός [griech.] add up, logical conclusion • Core of Aristotelian logic • Inference rules, all built according to the same pattern major premise All humans are mortal minor premise All Greeks are humans conclusion All Greeks are mortal subject Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  24. 24. Aristotle(384-322 BC) Ontology in Classical Greek Philosophy1615 Syllogisms • συλ-λογισμός [griech.] add up, logical conclusion • Core of Aristotelian logic • Inference rules, all built according to the same pattern major premise All humans are mortal minor premise All Greeks are humans conclusion All Greeks are mortal subject predicate Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  25. 25. Aristotle(384-322 BC) Ontology in Classical Greek Philosophy1615 Syllogisms • συλ-λογισμός [griech.] add up, logical conclusion • Core of Aristotelian logic • Inference rules, all built according to the same pattern major term major premise All humans are mortal minor premise All Greeks are humans conclusion All Greeks are mortal subject predicate Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  26. 26. Aristotle(384-322 BC) Ontology in Classical Greek Philosophy1615 Syllogisms • συλ-λογισμός [griech.] add up, logical conclusion • Core of Aristotelian logic • Inference rules, all built according to the same pattern middle term major term major premise All humans are mortal minor premise All Greeks are humans conclusion All Greeks are mortal subject predicate Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  27. 27. Aristotle(384-322 BC) Ontology in Classical Greek Philosophy1615 Syllogisms • συλ-λογισμός [griech.] add up, logical conclusion • Core of Aristotelian logic • Inference rules, all built according to the same pattern minor term middle term major term major premise All humans are mortal minor premise All Greeks are humans conclusion All Greeks are mortal subject predicate Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  28. 28. 1616 Ontology in Late Antiquity and Early Middle Ages Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  29. 29. Ontology in Late Antiquity and early Middle Ages1617 Aristotle‘s Categories Revisited • Porphyry of Tyros explains in his textbook „Isagoge“ the Aristotelian categories for beginners • In the Late Middle Ages the so-called „arbor porphyriana“ (Tree of Porphyry or „Tree of Knowledge“) is created as visualization of the Aristotelian categories • classic epistemologic ordering system, according to the semantics of botany Porphyry of Tyros (234-?? AD) Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  30. 30. Ontologie in der klassischen griechischen Philosophie1618 Porphyry of Tyros (234-?? AD) wikipedia.org Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  31. 31. Ontology in Late Antiquity and early Middle Ages19 Porphyry of Tyros (234-?? AD) Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  32. 32. 1620 Ontology in the Middle Ages Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  33. 33. Ontology in the Middle Ages1621 Medieval Scholasticism (12th-14th century) Thomas Aquinas (1225-1274) • Thomas Aquinas • Anselm of Canterbury • William of Ockham Anselm of Canterbury (1033-1109) William of Ockham (1288-1349) Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  34. 34. Ontology in the Middle Ages1621 Medieval Scholasticism (12th-14th century) Thomas Aquinas (1225-1274) • Thomas Aquinas • Anselm of Canterbury • William of Ockham • Problem of Universals: „Do Universals (Ideas) possess an ontological Anselm of Canterbury (real) existency?“ (1033-1109) • Realism „Universals are real!“ vs. • Nominalism „Universals are nothing but words and symbols!“ William of Ockham (1288-1349) Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  35. 35. Ontology in the Middle Ages1622 Occam‘s Razor • „Principle of Simplicity“ from Scholasticism • Among competing hypotheses, the one that makes the fewest assumptions should be selected • A theory is simple, if William of Ockham • it contains as few variables and hypotheses as (1288-1349) possible • that relate clearly logical with each other and • the subject to be explained can be logically deduced. „Entia non sunt multiplicanda sine necessitate.“ Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  36. 36. Ontology in the Middle Ages1623 • Ramon Lull applies ontology in the sense of the Aristotelian system of categories within his „Tree of Nature and Logic“ as first predecessor of a logical machine • Logic according to Ramon Lull is „the art and the science to distinguish between truth or lie with the help of reason, to accept truth Ramon Lull and to reject lie.“ (Raimundus Lullus) (1232-1316 Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  37. 37. 1624 Ramon Lull (Raimundus Lullus) (1232-1316 Arbor naturalis et logicalis, from „Ars Magna“ (~1275) Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  38. 38. 1625 Ontology in the Age of Enlightenment Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  39. 39. Ontology in the Age of Enlightenment1626 • John Wilkins finds out, that the inaccuracy of natural language impedes scientific progress • He developed the idea of a universal philosophical Language with the goal to represent the entire knowledge of the universe. John Wilkins (1614 – 1672) Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  40. 40. 1627 John Wilkins (1614 – 1672) ,A Doctor counted very able Designes that all Mankynd converse shall, Spite o th confusion made att Babell, By Character calld Universall. How long this character will be learning, That truly passeth my discerning.‘ (Ballad of Gresham College, 1663) Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  41. 41. Ontology in the Age of Enlightenment1628 • Gottfried Wilhelm Leibniz develops the idea of „characteristic numbers“ as a model for Aristotelian Logic, in the hope to solve logical problems with the help of a calculus. Gottfried Wilhelm Leibniz (1646 – 1716) Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  42. 42. Ontology in the Age of Enlightenment1629 • Immanuel Kant turns himself towards Epistemology (Kritik an der „reinen Vernunft“ eng: Critique of Pure Reason) • Epistemology: Immanuel Kant Categories are pure concepts of understanding (1724-1804) Quantity Quality Relation Modality Substance & Unity Reality Possibility Accident Plurality Negation Cause & Effect Existence Totality Limitation Reciprocity Necessity Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  43. 43. 30 Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  44. 44. 1631 02 Ontologies in Computer ScienceOpen HPI - Course: SemanticHarald Sack, Hasso-Plattner-Institut, Universität Potsdam Semantic Web Technologies , Dr. Web Technologies - Lecture 4: Knowledge Representations I

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