> If we have some kind of mental handicap that not allows us to perceive spectra properly, it's wrong to blame Plato for this.
I think Dawkins is simply using Plato's idea as an intellectual roadsign, not assigning moral responsibility. If I refer to Karl Popper when discussing falsifiability, I might simply be providing a convenient reference to the idea, not holding Popper responsible for the idea (which he isn't).
I think since he discusses the essentialism as an idea that needs to be dropped, he goes further than that - he seems to blame Plato (at least among others) for "infecting" us (taken broadly) with the essentialism. After all, the idea of essentialism has to come from somewhere, somebody had to invent it. To me, Dawkins assigns the fault for it to Plato. He does it in the very first sentence - "Essentialism—what I’ve called "the tyranny of the discontinuous mind"—stems from Plato".
Again, describing the origin of an idea isn't the same as assigning responsibility. Your use of words like "blame", "infecting" and "fault", and the associated tone, simply have no parallel in the article.
Also, correlation is not causation. Many of these classic ideas, found in the writings of Plato, Aristotle and others, were as much responses to the prevailing ideas of the time as they were a source or inspiration for those ideas. Our modern perspective is distorted by the fact that we may have only one writer's record of the ideas of a time, which may mislead us into thinking that particular writer originated the idea instead of reporting it.
"Infecting" is a direct quote from "We are still infected with the plague of Plato’s essentialism." and Dawkins uses the same word at least twice more.
>>> Our modern perspective is distorted by the fact that we may have only one writer's record of the ideas of a time, which may mislead us into thinking that particular writer originated the idea instead of reporting it.
This very well may be true, but since we and Dawkins share this perspective, and Dawkins offers no other suggestion and no other name but Plato and does not consider the possibility that this perspective might be wrong in any way, I think the conclusion that he operates on the assumption that this perspective - attributing essentialism to Plato - is correct would not be illogical, at least when we consider this particular article.
I think Dawkins is simply using Plato's idea as an intellectual roadsign, not assigning moral responsibility. If I refer to Karl Popper when discussing falsifiability, I might simply be providing a convenient reference to the idea, not holding Popper responsible for the idea (which he isn't).