The problem is that the concept sits much on appearance, and, in the twist of discussing the idea of race, it is too easy to have the appearance of being racist, the stance where the racial category has more importance than it really deserves.
Enter Princeton University history professor emeritus, Nell Painter, and her important book, "The History of White People", followed by Portland Community College dedicating the month of April as White History Month.
Intellectual appearance can be as confusing as physical human attributes, and the first thing one must say, that in this focus on "white history", there are no white supremacists in sight. These are enterprises where the examination of a "race", sits on a presumption for equity across the human species.
The problem is that historians are starting with a very misconstrued category. And yet it ought not to be ignored when the idea has played a significant role in how people thought in the past. The issue is that any history around appearance will only be skin-deep. The historian has to dig deeper, and hence, we have a difficult question in any social history, of how important is the concept of race as the historical force we apply to the past.
I think that the Portland Community College project is slightly misconstrued in arguing that "whiteness does not simply refer to skin color, but an ideology based on beliefs, values, behaviors, habits and attitudes", which I take as an argument that appearance becomes the whole ideology. However, where then are other important ideological categories where significant discrimination has arisen -- class, religion, politics, gender, and the appearance of physical disability? It is probably not the intention of the advocates to overlook these factors. I am sure that they would recognize these other categories in a broader social history. Nevertheless, some differences in the historical grouping of one "racial identity" have to be taken into account. It is undoubtedly true that white supremacists of the past uniformly worked from an ideology of whiteness, however, that is not true of every person who could be included into a single racial grouping. Nell Painter referred to those who felt discriminated, in the past, as Catholics and Jews. We clearly have here categories which are far more important than the physical appearance of the person.
There is a presumption of whiteness when thinking about these religious or cultural identifications; however, we know that the presumption is not necessarily true. Whiteness does have something to do with the discriminatory response. There is much made of "Europeanization" in third-world colonialism, however, what is missed is the line between Northern and Southern Europe, where the northern end sat on the idea of a purer whiteness, in contrast to darker hair and skin tone of the Mediterranean peoples. And yet the Spanish and Italians account for a larger part of the history in europeanising the globe. Physical appearance does not go deeper enough for a fuller understanding in social history.
Furthermore, while the idea of mirroring back upon the perpetrators of discrimination has merit, we can get confused about what is being reflected back. There is a human tendency to notice different physical appearances when it is not common to the community we inhabit. Indeed, the same is true for foreign cultural habits the particular persons are not use to encountering. However, the history we are reflecting upon is changing and diverse. Cultural habits changes in both directions, even if it happens unevenly between groupings. Hence, the historian has to be careful about what is being reflected back in the contemplation of the past. Is it the fears or the concerns of the historian's own idea or practice of "race”? There was (and perhaps still is) a construction of race in the minds of many. The problem is that it is a misconstrued concept if we start with a larger framework of what it is to be human. And this is a matter of taking the radical postmodernist argument and placing it on its head. The radical postmodernist took the wrong turn in denying the category of human, and played hard in the world of fragmentation. However, for fairness to all living things (including that which is not human), what is the most important category in history -- race or what it is to be human? That was the question of the European Enlightenment, and for having its historical origins there (and that's debatable in its originality), it can be not be characterized by the appearance of a presumed whiteness.