[en] The present discussion of resistive instabilities in cosmic plasmas emphasizes the qualitative changes that occur when theory proceeds from simple cases, where symmetry allows exclusion of one or two space coordinates, to the general 3D process. Due to a strong localization of resistive effects, the resistive instability occurs on a time-scale potentially much faster than magnetic diffusion for large values of the Lundquist number. It is shown that the general magnetic reconnection is adequate for describing 3D resistive instability processes, including cases where the magnetic field has no such singularities as magnetic nulls. 36 refs