Marcion’s Gospel and the Question of Theological Tendency

Marcion’s detractors condemned him for excising material to suit his theological principles, but also mocked him for failing to do so consistently. Recent defenders of the priority of his Gospel have tended to dismiss such charges, but explain ‘Lukan expansion’ on similar grounds. Can ‘theological tendency’ be used in discussing Lukan textual tradition without ending up in a self-fulfilling circle.