- Fill an empty barrel with one serving of any unpoisoned drink.
- Add the same drink, but now poisoned.
- The whole barrel stays unpoisoned.
Now the other way round:
- Fill the barrel with a poisoned drink.
- Add a serving of an unpoisoned drink.
- Now we have got a poisoned barrel.
Both barrels contain exactly the same: One poisoned and one unpoisoned serving, but the outcome depends on what is filled in first. This is highly illogic.