I review the proposal made by Sigurðsson (2011) that null arguments follow from third-factor principles, as in Chomsky 2005 . A number of issues remain unclear: for instance, the kind of topic that licenses null arguments in Modern Germanic, including Modern English. I argue that Old English is pro drop and add to the discussion Frascarelli (2007) started as to which topic licenses a null subject. I agree with Frascarelli and Hinterhölzl (2007) that the licensing topic in Modern Germanic and Old English is an aboutness-shift topic. I also argue that verb movement to C is necessary to license the empty argument in the modern Germanic languages (including Modern English), but not in Old English, since agreement is still responsible for licensing in that language, as in Italian.