The rapid changes in the relationship between humans and machines evidence a progressive delegation of some human activities to machines. Among those, there are not only physical activities but also intellectual and social activities. However, we deem that even the most powerful computers should be considered as tools created and used by humans and not totally autonomous and independent subjects. Therefore, we see a theoretical objection to machine ethics as the enterprise of adding an ethical dimension to some machines. Rather than trying to implement ethical behavior in machines, we suggest extending the traditional ethical framework. This extension should include also problems concerned with the behavior of machines towards users and other machines in the perspective of the centrality of humans with respect to machines.