It's not exactly a secret that Libertines love to debate. Among themselves, with other Pentacle mages, even with Sleepers - it's the ferment, the movement, the equality of a free flow of ideas that matters. Things have been pretty tense around Shodan lately, so he decides to take the edge off by rekindling that custom of talking about issues that matter like normal human beings.
To that end, he placed posters advertising the event right past the Circle's main entrances - not his finest creation, to be sure, but they proclaimed the debate's place, time and topic, which should be enough. And the Libertine makes good on the promise of snacks - apart from foldable chairs, there are also tables placed in the Assembly hall, creaking under the weight of soft drinks, chips, fruit, M&Ms and a myriad other kinds of things to chew on.
He is not particularly worried about attendance - but then again, Shodan is rarely seriously worried about anything. Aurora has expressed desire to talk about something interesting, Morgan floated the idea of an Atlantean study group so she might find this interesting (and with any luck she'll bring the pink-haired one along, so that Shodan has the opportunity to hear her speak more than one or two sentences at a time). Hell, maybe even Campanella will attend, out of curiosity if nothing else. Or maybe some other people will come along. There's space and refreshments aplenty.
In any case, the Obrimos does not seriously consider that mages could possibly refuse the offer of free food.