I want to know the answer to the following question:
Al-Farabi concluded a perfect vacuum was incoherent using what?
All the background I'm provided with is that "In the medieval Middle Eastern world, the physicist and Islamic scholar, Al-Farabi (Alpharabius, 872–950), conducted a small experiment concerning the existence of vacuum, in which he investigated handheld plungers in water.[unreliable source?]". Is that enough to answer the question?
Answer: yes