text: 3.3 World knowledge 
  
  The bulk of evidence about commonsense knowl- 
  edge captured in BERT comes from practitioners 
  using it to extract such knowledge. One direct prob- 
  ing study of BERT reports that BERT struggles 
  with pragmatic inference and role-based event 
  knowledge (Ettinger, 2019). BERT also struggles 
  with abstract attributes of objects, as well as visual 
  and perceptual properties that are likely to be as- 
  sumed rather than mentioned (Da and Kasai, 2019). 
  The MLM component of BERT is easy to 
  adapt for knowledge induction by ﬁlling in the  Furthermore, different probing methods may 
  lead to complementary or even contradictory con- 
  clusions, which makes a single test (as in most stud- 