I have been thinking seriously about sedevacantism a lot the last year or so, and I went to a Gerry Matatics conference in my area to get his insights.  When it was over, I asked Gerry about whether the church could be considered visible if there were no pope and no plans to elect another.  What he, this immensely intelligent and learned man, said astounded me.  When I asked how the church could be visible if his claim was true, he simply said, "You can see the priest."  That is, he implied that the visibility of the church meant that its representatives could physically be seen!  Taken aback by such a simplistic explanation, I said, "You can say the same about a Protestant minister."  He then said, "Oh right," and then made the familiar argument about the interregnum after the death of every pope.  This was after an 8-hour talk (which was supposed to be 4, but with Gerry times are to be taken with a grain of salt) in which he didn't address the visibility issue once.  This matter is the reason I am not a sedevacantist.  I haven't seen the question answered satisfactorily anywhere.  

Yes, I think it was visible right after Pentecost because there was a validly selected pope and validly ordained bishops.  Precisely in this consisted its visibility.  The facts that this group was for the most part not physically visible, due to small size and impoverishment, and that it might have been hard to find this group, are immaterial to the visibility question.  Otherwise you would have to say a protestant denomination that became large enough had visibility, which would be false by the protestants' own admission (they don't claim visibility), or that there are degrees of visibility, which there are not (at least not in the context of Catholic theology: that is, either we have a hierarchy representing the church to the world, however difficult to discern, as in the catacomb days, or however badly it may govern, as today, or we don't).  All that matters for visibility is the existence of this hierarchy.  That was my point against Gerry.

I very much want to side with you; it would make a lot of things easier.  But I'm not seeing the evidence on this point.

This is old news, but none the less very relavent.

Well in the Western Schism, a lot of people did not know who the Pope was, this kind of situation is not unheard of, so it has an historical basis from which to draw from. But the Pope as the vicar of Christ is not the whole Church, because sometime he has to die, and the Church will still exist in an interregnum, whether there is a Pope or no. Christ is the head of the Church, the Pope represents Christ, if the rep dies, Christ still remains head, and the Church still exists. Even if the interregum were an extended period, it is no real stick against the argument in question, rather that it has happened before, and that ergo is possible and feasible.
However, the priest as a vassal of Papal authority, represents the Pope, who reps Christ, and after all he represents Christ in the confessional, is a visible part of the Church hierarchy.

The main sticking point is that we always have to have a pope, but what is overlooked is that all throughout history there were times where there was no pope, and the majority did not know the true pope, or simply did not know between various claimants. The visiblility issue I believe was settled by Our Lady at LaSalette when she said that the Church would be in eclipse, and this is straight from heaven, from our lady. And some prophecy said some thing said that the Church will be punished because the majority of her members, will become so perverted. that the Church would sink deeper and deeper until it would seem to be extinguished, and the succession of
Peter to have expired, and after this, would be exalted in the sight of all doubters.

But since I am no authority, I cannot judge the Pope, but as Catholics, if we see heresy, we are bound to condemn it and it propagator, no distinction is made.