Newton Did Change His Views from Certainty to Probability

Kirsten Walsh has criticized my interpretation of Newton’s view on the certainty of his new science of color, namely, that it shifted through his long career from one of certainty to probabilism. I defend my view by further considering his statements on certainty in his Optical Lectures, “New Theory about Light and Colors,” Query 31 of the Opticks, and Rule 4 added to the Principia in 1726.