 Nachum Dershowitz and Yuri Gurevich and (independently) Wilfried Sieg have also argued that the Church-Turing thesis is susceptible to mathematical proof. Sieg focusses on Turing’s argument I, offering an axiomatized version of it in his 2002 and 2008 (for a critique of Sieg’s approach see Shagrir 2006). In their 2008 Dershowitz and Gurevich offer “a proof of Church’s Thesis, as Gödel and others suggested may be possible” (2008, 299), adding: