  In the framework of such basic principles as local gauge invariance,
unification of the weak and electromagnetic interactions and spontaneous
symmetry breaking in the Standard Model the most economical and simplest
possibilities are realized. We discuss the problem of neutrino masses from the
point of view of economy and simplicity. It is unlikely that neutrino masses
are of the same SM origin as masses of leptons and quarks. The Weinberg
effective Lagrangian is the simplest and the most economical, beyond the
Standard Model mechanism of the generation of small Majorana neutrino masses.
The resolution of the sterile neutrino anomaly and observation of the
neutrinoless double $\beta$-decay would be crucial tests of this mechanism.
