I used to think that the 'possible worlds' idea was just one of those clever philosophical tricks. You know: you try to imagine whether (for example) there could be possible world where a person had all the physical traits of a human being but had no conscious life. If such a world were possible, then mind - consciousness - is something over and above the physical brain. Zombies, of the philosophical ilk, exist and dualism is back in fashion.
And then, the other day, I was sitting in my parents' garden, overlooking the sea and I suddenly realised what a wonderful emotional trick this 'possible worlds' idea could be. A radical form of psychotherapy. I have struggled for a long time being childless. It's one of life's disappointments and, well, it does - now and then - affect me on a deep level.
But what if I undertook my own psychological treatment?
Imagine a truly infinite number of possibilities existing out there in a truly infinite number of possible worlds. Being childless is a contingent fact that holds in this world. In another world, it doesn't: there, I have all the children I could possibly want.
Realising this, steals from my tragedy its eternal stamp, the branding which scars my soul and leaves me wounded. I can smile across the abyss of space and time and greet my other self who is living the life I only dream of having. I can rest in my contingent incompleteness because somewhere else I'm fulfilled.