The journal Biology & Philosophy has published a special issue on the philosophy of CRISPR-Cas. Thomas Pradeu has written the introduction and together with Jean-François Moreau he presents a commentary to Eugene Koonin’s target paper.
In the commentary Pradeu and Moreau defend an extended view of CRISPR-Cas immunity by arguing that CRISPR-Cas includes, but cannot be reduced to, defence against nonself. CRISPR-Cas systems can target endogenous elements (for example in DNA repair) and tolerate exogenous elements (for example some phages). They conclude that the vocabulary of “defence” and “nonself” might be misleading when describing CRISPR-Cas systems (PDF of final draft).