 Taken at face value, however, the requirement of impossibility of interference seems over demanding, as it is never completely impossible for others to constrain me. It is not impossible that I be stabbed by someone as I walk down the street this afternoon. Indeed, the possible world in which this event occurs is very close to the actual world, even if the event is improbable in the actual world. If the mere possibility of the stabbing makes me unfree to walk down the street, then unfreedom is everywhere and the achievement of freedom is itself virtually impossible. To avoid this worry, republicans have qualified their impossibility requirement: for me to be free to walk down the street, it must be impossible for others to stab me with impunity (Pettit 2008a, 2008b; Skinner 2008). This qualification makes the impossibility requirement more realistic. Nevertheless, the qualification is open to objections. Is ‘impunity’ a purely formal requirement, or should we say that no one can carry out a street stabbing with impunity if, say, at least 70% of such stabbings lead to prosecution? Even if 100% of such stabbings lead to prosecution, there will still be some stabbings. Will they not be sources of unfreedom for the victims?