(scientific method)
On the other hand, *somebody* had to be the first, and the classical Greeks whose work he was building on weren't big on abstracting their methods---especially the "natural philosophers" who really could be seen as laying the groundwork for the modern experimentalist view of the scientific method. (The pure mathematicians sound more like their modern counterparts, but then as now the mathematicians seem to have been widely felt to have a screw loose.)
Remember, too, that while those earlier thinkers look like contemporaries to us and probably did to ibn al-Haytham, they weren't really. It's not like Galen and Euclid and Aristotle ever had the opportunity to sit down over coffee and say "Now, what is it we're really doing here, gentlemen?" and synthesise a clear model of their working methods.