Ludger Jansen
Research Projects

"Just as firesticks rubbed against each other send forth fire, so also do puzzled souls through their inquiry send forth the ligth of truth." (Ammonius, In Cat. 80.7-9)
"Denn die Fähigkeit zu denken beginnt wahrscheinlich an derselben Stelle, an der die Fähigkeit, sich selber Schmerz zu bereiten, beginnt." (Alfred Meusel, Die Konkurrenz in soziologische Betrachtung, in: Die Gesellschaft 2, 1929, 326-347, 347)

Social Ontology

What kind of entities are groups or states? What are their criteria for identity and individuation? What is the relation of social entities to their members? If social entities are social constructs, what rules govern their construction? And, turning into political ethics: Are there any norms how we ought to construct such social entities?
I am working on a monograph on this topic. Hitherto I gave several talks on the subject matter and wrote several papers, some of which are already forthcoming. I agreed to write a review article on recent work in social ontology for the "Zeitschrift für philosophische Forschung".
Read more about this project

History of Ancient and Medieval Philosophy, especially Aristotle and Aquinas

My three theses (MLitt, MA, PhD) are all concerned with the Aristotlian Philosophy or its medieval tradition in Aquinas. My PhD-thesis on Aristotle's theory of capacities was published as a monograph ("Tun und Können", 2002) In addition, I published several articles and reviews concerning Ancient and Medieval Philosophy. I also contributed to two reference books concerning ancient philosophy in general and Aristotle in particular. I hope to be able to continue my research in ancient and medieval philosophy and plan to write articles on Aristotle's treatment of relational terms and on Plato's Cratylus.


What is the ontological status of dispositions? How do we ascribe them? What is their relevance in (the philosophy of) science? Do we need them in ethics, too?
In my Ph.D. thesis I reconstructed Aristotle' theory of capacities in Metaphysics IX (published as "Tun und Können", 2002). In addition, I did some systematic work on the ontological, scientific and ethical aspects of dispositions and capacities. Some of the work has been published, but several papers are still forthcoming.
Read a preprint version of "Dispositionen und ihre Realität" (pdf-file)


Problems of the justification of norms in different cultural and in multicultural contexts; ethical problems of social structures. These research interests are closely related to my interest in social ontology. Some short pieces on these topics have been published.

Philosophy of Religion

Especially hermeneutical aspects of sacred texts and the relation between faith and understanding.
Having written my theological thesis as well as an article on Aquinas' hermeneutics, I have already drafted an article on the semiotic analysis of Bultmann's demythologisation. I also contributed to a dictionary of philosophical concepts in theology.


I am preparing a research project on the logic of concepts in co-operation with Niko Strobach, University of Rostock. Several presentations of the project on several conferences earned lively interest. A first paper has now been published in a refereed collection.
Read more about concept logic (Word-document)
Read a preprint version of "The so-called materially valid inferences and the logic of concepts" (pdf-file)

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