Here is a standard proposed by @liminal above: defining gender is problematic for me because it seems to necessitate that I be able specifically identify a group of people and then proceed to claim there is something universally essential about that selected group.
In social science, such a standard would mean that no one could identify any group of people at all. However, we do not require universality in order to specify a group, and to use universality as a standard is essentially a red herring, due to the fact that it doesn’t exist anywhere in social science.
When we seek to define something—some kind of behavior, such as say “active” listeners compared to “passive” listeners compared to “shy” listeners (these are made up categories), we often perform something called a “factor analysis.” To put it simply, a factor analysis helps us group together various pieces of information that we have into groups that seem to be measuring much the same thing.
We make up a name for this factor that we think is descriptive of the kinds of bits of information that go into that factor. No one bit of information is the same for all members of that group, yet when you count a large numbers of bits of information, it becomes clear that it is sensible to group them together.
There is no one thing that is universally essential to the group we call “women.” There are a number of factors that some in the group share with others in the group, and there are other factors that are not shared in one part of the group but are in others. This, of course, makes the definition of the category somewhat fuzzy at the edges, where the idea we call “woman” blends into the idea we call “man.” This is true for every “factor” we define. Social science is squishy, not precise like hard science, and the standards for hard science are inappropriately applied to questions of social science.
To define a “real” man or a “real” woman would not be to provide a definition that excludes all members of the other gender. You don’t have to do that for the categorization to be useful. And defining a category and then sorting something into that category does not mean the category makes sense or that the individual case is appropriately sorted into that category. So this is why social scientists always qualify their statements with “on average.” Social scientists know that there could easily be significant variation that would make one observation look as if it belongs in a different category, even though it is in this category due to a priori categorization.
So yes, I could define a real man or a real woman if you gave me enough examples of each to study. I would come up with factors that distinguish between the two for a wide variety of individuals.
It goes without saying that you need to look at all kinds of individuals in order to create categories. When we sort things—say rocks—we don’t say that we are going to define small rocks, but we’ll exclude big rocks from our definition. That makes no sense.
So definitions of categories do not need to stand on their own. If fact, they can’t stand on their own. But, this question keeps on suggesting we should apply hard science standards to the subject: either/or situations. This question seems to be arguing for a more nuanced and fuzzy definition of gender. I don’t know what the fuss is all about, since that’s the way it is, anyway.
The real issue is about the natural human tendency towards reductionism. People want to make things as simple as possible—to have as few categories as possible. So, since the fuzziness at the boundary between men and women—or “real” men and “real” women—is not that broad, most people have no problem reducing the issue of gender to two categories. It works in the vast majority of cases.
When the people who are living on the border between these categories start to make themselves more visible, it upsets people. I don’t think it upsets people so much because they are offended by mixed behavior, but because it ruins their simple system for categorizing people. Most people don’t like complexity. They prefer simplicity, and multiplying the number of genders is confusing, and, most probably believe, unnecessary.
These categories—male and female—are not arbitrary. The are subjective, but they also are useful, except at the edges where they bleed into each other. They are useful and they are convenient, and the border between them where the fuzziness lies is not that wide. That’s why people use them. And given that, for most people, expanding the number of categories doesn’t really help them in day-to-day life, those categories will remain the way most people think about the concept of gender.