And the Hi, I'm Peter Adamson, and you're listening to the History of Philosophy podcast, brought

to you with the support of the LMU in Munich, online at

www. History of Philosophy.net. Today's episode, Into Thin Air,

Avicenna on the soul.

One of the most popular weapons in the arsenal of contemporary philosophy is the thought experiment.

It's gotten so you can't venture into any department of philosophy without being asked whether you'd be willing

to shove someone off a bridge to block a train before it hits a bus full of school children.

Or suppose that your best friend stepped into a Star Trek style teleportation device, and two identical people popped out at the far end instead of just one.

In such a circumstance, would you be willing to buy both of them a birthday present?

Thought experiments are nothing new though.

Already in Antiquity Aristotle had asked what would happen if there were another universe.

He concluded that the Earth in that universe would need to converge on the same natural place as the Earth here, since the two Earth's share in nature.

Thus, the two universes couldn't possibly remain distinct.

Which reminds me of my favorite example of a thought experiment from late Antiquity.

Platinus wonders whether an eye on the outside of a second universe placed next to ours would be able to see our own universe.

He concludes that it would not, since sensation works through a universal sympathy that binds

our single universe together.

The use of this method in philosophy raises a number of interesting issues,

especially when we are considering scenarios like these that are so remote from our experience.

Here it may help to draw a distinction

between strict impossibility and inconceivability.

It is not interesting or helpful to ask what would happen

...