Just as the title says. There was a philosopher who said that you should jump into a fire if you think it might not exist and see how it goes. I cannot find it on google, maybe I am typing in the wrong keywords. I think it might have been Locke or Hume.
How about this?
The celebrated Arab commentator Avicenna (ibn Sīnā, 980–1037) confronts the LNC [Law of Noncontradiction] skeptic...: “As for the obstinate, he must be plunged into fire, since fire and non-fire are identical. Let him be beaten, since suffering and not suffering are the same. Let him be deprived of food and drink, since eating and drinking are identical to abstaining” (Metaphysics I.8, 53.13–15).
Source: Stanford Encyclopedia of Philosophy > Contradiction > Section 1. LNC [Law of Noncontradiction] as Indemonstrable.