Ruby's Greek Thread

[Koen G]

In a strict categorical (no pun intended) case like this, you can prove a negative. Or basically in any case that involves simple observations. Proving that I am holding a pen in my hand is just as easy as proving that I have no pen in my hand. But in practice, proving a negative is often harder because it involves disproving a whole range of scenarios. And after that, new scenarios can probably still be thought of, keeping the ball rolling.