In April 1975, Halfwassen appeared as a 16-year-old contestant in the quiz programme Der große Preis with Wim Thoelke on the subject of ‘Louis XIV’.
Two years later, he established the Hans-Georg Gadamer Endowed Professorship for Humanities at the University of Heidelberg, which he continuously supervised and organised.
Since March 2014, he has been a Fellow of the Marsilius-Kolleg at the University of Heidelberg and has been working on the philosophical redefinition of the relationship between matter, determinacy and freedom.
He was awarded the Rudolf Meimberg Prize of the Academy of Sciences and Literature (2003) and an honorary doctorate in philosophy from the State University of Athens (2014).
Halfwassen was co-editor of the series Quellen und Studien zur Philosophie, De Gruyter publishing, and of the journal Philosophische Rundschau, Mohr Siebeck publication.
Among other things, he recently worked on the commentary for a bilingual edition of the testimonies to Plato's ‘Unwritten Doctrines’.