  We have recently proposed a new scenario where blazars are classified as
flat-spectrum radio quasars or BL Lacs according to the prescriptions of
unified schemes, and to a varying combination of Doppler boosted radiation from
the jet, emission from the accretion disk, the broad line region, and light
from the host galaxy. This mix of different components leads to strong
selection effects, which are properly taken into account in our scheme. We
describe here the main features of our approach, which solves many
long-standing issues of blazar research, give the most important results, and
discuss its implications and testable predictions.
