Would this invalidate the papacy? since if ordenation of a Pope is given without intention, then he is not a valid pope. This would in effect break the direct lineage from Peter?
The Pope’s election is not an ordination. Usually, the Pope is already a priest and probably a bishop, so no ordination is necessary. Even if the Cardinals were to elect a layman as the next Pope, his ordination as priest and bishop would be separate from the actual election.
Even where a sacrament is concerned, the requirement of “intent” is always very broadly interpreted. An atheist can baptize if necessary as long as he uses water, employs the proper form of words, and intends to “do what the Catholic Church does when she baptizes,” even though the atheist presumably does not believe that the baptism is actually “doing” anything to the recipient. The Church does not want people living in constant doubt that the sacraments they receive are valid just because they can’t know what the minister of the sacrament is really thinking.
Likewise, it goes against the notion of God’s protective love for his Church to think that an antipope could sit unchallenged on the papal throne for an extended period of time while everyone believed him to be the real Pope. There are people who believe that the last few Popes haven’t “really” been Pope, and even a few who’ve tried to “solve” the “problem” by having themselves elected Pope (see Leopard’s earlier post for some examples in the United States), but generally the idea that the Church could be fooled into thinking she has a Pope for so long isn’t much preferable to the idea that God would just let the Church cease to exist altogether.
Keep in mind, also, that the papal office is more like the American Presidency than like a hereditary monarchy. One “succeeds” to the office by being chosen according to the system currently in place. There is no necessary direct connection to one’s predecessor, and the line is not broken if there is a brief vacancy (as there always is between the death of one Pope and the election of the next). So even if an invalidly elected Pope managed to slip through and serve out his entire reign, the valid succession would be restored as soon as he died and another was legitimately elected in his place.
In other words, even if the Church is ultimately wrong about which papal claimant was the real Pope during certain parts of the Western Schism, the election of a totally different guy at the end of said schism fixed the problem, with no permanent damage to the succession.
Usagi