Martin McGuinness responded to criticism of the Tyrone Volunteers Day parade in Castlederg by arguing last week: "The parade which is about to take place is a parade that is absolutely and totally confined to the nationalist and republican areas of the town and it doesn't impinge on the unionist communities."
Hmm. By that logic, he wouldn't raise any objection if a parade celebrating the actions of the Paratroop Regiment involved in Bloody Sunday was held in an exclusively unionist/loyalist area of Londonderry.
He's wrong – seriously and dangerously so – at a number of levels. A parade commemorating and celebrating two IRA members, in particular, and the IRA campaign in general does "impinge" on the unionist communities.
It does send out a particular message: that message being that the IRA campaign and the lives of two men killed by their own bomb are worth commemorating.
And that, in turn, sits uneasily with Declan Kearney's comments in this newspaper last month that "there is a moral imperative to ensure future generations grow up in a better place than we did".
How can they grow up in a better place if republicans continue to promote the logic that parades are okay as long as they stay in their "own'" areas?
Because, once you accept that logic, once you embrace the principle that Northern Ireland should be divided into us-and-them areas for parades and commemorations, then you close the door to a shared future and build a wall, upon which you paint: "This is our territory."
How, then, do you build the shared schools, the shared housing and the shared sports and social facilities? Well, you don't.
You simply kid yourself that the space between the us-and-them barriers is a "neutral" space open to all: when it would, in fact, be no more than somewhere to walk your dog, or wait for public transport.
Another problem with McGuinness's argument that the Castlederg parade is acceptable because it is "confined" to nationalist and republican areas is that it carries the suggestion (and deliberately so, I suspect) that an IRA commemoration is welcome and wanted in those areas.
It reminds me of the dreadful bigotry I used to hear when I was growing up in the 1960s: "Sure, all Catholics are really republicans and IRA supporters."
Is that what our deputy First Minister is really arguing? Is he really trying to say that every single non-unionist in Castlederg approved of the IRA?
Maybe he is. Gerry Kelly, a Sinn Fein MLA and former junior minister, will address the parade: and no doubt he will praise the campaign and the two bombers blown up on their way to kill others.
The irony, of course, is that those bombers were involved in a terrorist campaign to bomb the British out of Northern Ireland and now they are to be praised by a Sinn Fein representative who sits in a devolved government in a Northern Ireland which remains firmly locked into the United Kingdom.
And that's the ultimate danger with this type of parade. It is a propaganda exercise, pure and simple. It's not about the celebration of culture, or values: it's about the celebration of terror and violence.
And, in supporting it and in sending along a very senior member of their leadership team, Sinn Fein (and particularly Martin McGuinness) is sending out an unambiguous message to everyone within unionism: when it comes to the terror campaign, we remain unashamed and unapologetic.
In other words, the right to sustain their own areas and the right to commemorate bombers and snipers will always trump the need to build a shared society, either in Northern Ireland, or in any future united Ireland.
But unionists/loyalists needn't think I'm letting them off the hook on this issue, either. Whether they like it or not, most non-unionists (and quite a few unionists as well, as it happens) are uncomfortable with what seems to them to be the triumphalism and inherent bigotry of loyalist parades. They believe that unionists also celebrate violence and violent men.
So there's the real dilemma for the Parades Commission, its possible replacement and Richard Haass. Parades today are propaganda exercises: one-sided exhibitionism to remind the "other" side of their existence and their refusal to go away.
Encouraging people to walk "where you're wanted" merely encourages Balkanisation. Trying to re-route, stop, or compromise usually leads to stand-offs and riots.
The Parades Commission can never get it right and please both sides. No third party/organisation can hold the ring for the opposing sides.
So, the toughest question of all is whether both sides would be willing to rethink their whole parading/commemoration strategy in exchange for laying the framework for a genuine shared political/cultural/social future with each other?
I don't know the answer to that question, because I don't know how many people actually want a shared future involving the other side.
But one thing I do know: parades and commemorations are the moving interfaces of politics here; regular reminders of how far we have yet to go before we meet for a solution rather than remain parted by continuing stalemate.
This is the most important issue facing all of us – and I do mean all of us – because it is this issue which has the potential to undermine and eventually destroy both the political and the peace process.