“An anecdote had it that he [‘Ali an-Nashi’, d. 976] was once engaged in a disputation with al-Ash’ari… The disputation was in progress when, for no reason at all, he slapped al-Ash’ari’s face. Taken aback, Ash’ari demanded the reason for his opponent’s unprofessional conduct. Nashi’ said: ‘That is God’s doing, why get angry with me?’ Beside himself, Ash’ari exclaimed, ‘It is you doing alone, and it is bad conduct exceeding the bounds of decency in a disputation!’ Whereupon Nashi’ replied triumphantly: ‘You have contradicted yourself! If you persist in your doctrine, then the slap was God’s doing; but if you have shifted from your position, then exact the equivalent!’ Whereupon the audience broke in peals of laughter; Nashi’ had made his point that humans are responsible for human acts.”

The Rise of Colleges, Makdisi

I suppose that many of my readers will be familiar with the perennial debates in Christian traditions over the nature and extent of God’s knowledge and determination of human actions. As the above story should demonstrate, the same sorts of questions early on arose in Islam, and became topics of heated debate- and at least one very clever “visual aid.”