Today is Maybe Day, a day inspired by the late writer Robert Anton Wilson. It was his hope that on this day people of all creeds and beliefs would come together and chant, "Jesus is the only son of God, maybe" "Hear O Israel, the Lord thy God is one, maybe" and "There's no God but Allah, maybe, and maybe Mohammed is his prophet." At this point the world would suddenly become a far saner place.

Of course, it is not necessary to congregate to celebrate Maybe Day. It is not even necessary to say those words out loud. Simply reading the words in a newspaper or a blog is enough to participate, and in that spirit may I personally thank you for joining in and making Maybe Day 2009 such a success.

But be careful: the Wars of the Certain rage around us. As Wilson pointed out, "certitude is seized by some minds, not because there is any philosophical justification for it, but because such minds have an emotional need for certitude." By celebrating Maybe Day you risk abuse from those people, the Certain, who object to the unsure, the sceptical or the deeply confused. In The God Delusion, to give one example, Richard Dawkins engages with the monotheistic viewpoint with argument, but he dismisses agnostics with insults. They are, in Dawkins' view, the theological equivalent of the Lib-Dems, "namby-pamby, mushy pap, weak tea, weedy, pallid fence-sitters."

To sympathise with the Certain for a moment, they do not have it easy. There are billions of people on this planet and they all have wildly differing ideas about politics, ethics, theology, art and science. It is very hard for the Certain to insist that their own position is the only right, true and undeniable one, especially if they posses a basic knowledge of mathematics and probability. You can rationalise away this problem by deciding that the rest of the world is basically composed of idiots, but it is rarely a good idea to admit this publicly. We live in a culture where megalomania is frowned upon.

Then there was the relentless march against certainty that took place in the 20th century. The work of Einstein, Joyce, Picasso, Heisenberg, Leary, Jung, Lorenz and countless others showed that we do not possess a single model of our universe that can account for all that we find around us. Instead, we have a number of contradictory models, each with their own strengths and flaws, and we must decide which is the most practical to adopt for our current needs. Our task, therefore, is to keep testing those models, to evaluate probabilities and to reject once-treasured ideas when more suitable replacements are found. This is not to say that all models are equally valid; rather, it is to say that all models should be recognised as incomplete, flawed and useful only to a point. To quote Robert Anton Wilson again, "I don't believe anything, but I have many suspicions."

Maybe Day allows us all to cast off our certainties, if only for one day. It is a day when you are can allow yourself to be sceptical of your favoured models without any danger of damage to your ego. The Certain are invited to climb up on the agnostics' fence and join them for a cup of their famous weak tea and a plateful of mushy pap. By sitting up on the fence, they'll be able to see the whole territory. Maybe the Certain will be surprised by this view. Maybe they will see that the important question is not which side of the fence they should defend, but what idiot put the fence there in the first place, and exactly who benefits from leaving it up?