Seevacantism is a theological position embraced by a minority of Traditionalist Catholics which holds that the Papal See has been vacant since the death of Pope Pius XII in 1958 (or, in some cases, the death of Pope John XXIII in 1963). Sedevacantists believe that Paul VI (1963–1978), John Paul I (1978), John Paul II (1978–2005) and Benedict XVI (2005-) have been neither true Catholics nor true popes, but rather notorious heretics, by dint of having allegedly espoused Modernism.