|You know it makes sense|
Data is one of the most interesting characters in Star Trek TNG. A central theme for Data is his quest to become more human. During the course of TNG, we see him evolve in many ways. He is always, however, limited—until the film Generations—by his lack of emotion.
There is no doubt that Data becomes more and more socially competent and aware as the series progresses. But is this actually progress towards humanity? I don't mean he remains less than human. I mean that he has, in many ways, humanity to start with.
Data is, throughout the series, one of the most generous and least judgmental characters. This is seen in "The Neutral Zone", at the end of the first season, when three people from the twentieth century are revived, and some of the crew (including Riker) express attitudes of rather unreasonable disgust. But not Data, who is ready to be friendly with anyone.
In the second-season episode "Pen Pals", Data pleads for the Enterprise to save a planet about to be destroyed by natural forces. He has rather improperly been in contact with a child there by radio. Captain Picard is unwilling to help because of the Prime Directive—an early example of it being taken to the point of absurdity—and there is a rather odd debate among the senior staff in which they consider among other things whether there is a cosmic plan involving the planet being fated to die. (Dr Pulaski, with her usual good sense, comments that the rigid idea of the Prime Directive is "callous and even a little cowardly".) Eventually Picard relents, and the planet is saved, without the inhabitants becoming aware of the Enterprise (the child's memory is erased). Captain Picard tells Data that "Remembrance and regrets, they too are a part of friendship... and understanding that has brought you a step closer to understanding humanity." What? Data cares about a child, tries to make the others see the inhabitants as real people rather the subject of theory, and goes beyond a rigid rule to save a whole planet. Captain Picard was initially prepared to let billions of people die because of the rule book, and now he pontificates to Data about how he has taken a step towards the humanity which he, Picard, presumably exemplifies. He changed his mind—good—but which of the two is the better example of humanity? Remind me again which one is just following a program?
The Prime Directive, of course, requires more detailed discussion. But I will note here that the original concept was not interfering in the natural development of a society's development. In "The Paradise Syndrome" (TOS), for example, the Enterprise rescues a planet from an asteroid, but the inhabitants can't be allowed to know about it, and this does not seem to be controversial. Arguably what is at stake here is not the Prime Directive but a sort of fanatical fundamentalism about it. Captain Picard, who is (at least in the earlier part of TNG) a repressed and uptight character, not surprisingly takes a rigid view at first. But he eventually relents—and it's interesting why he does. He hears, accidentally, the voice of the child calling for Data. His emotions are engaged, and he realizes the right thing to do. His is the response of the person who gives to charity when there is a human face to relate to, a pretty child on a poster for emotional appeal. Obviously that's better than not to be moved at all. But Data is not motivated not by easy emotion, since he doesn't have any; his is a more deeply human response.
In "Deja Q", the episode where Q is expelled from the Continuum, everyone is, naturally enough, very down on Q. Everyone but Data. He is not exactly friendly at first, and he pulls up Q when he doesn't toe the line, but he speaks up for him when it is appropriate, treats him with basic courtesy, and he tries to save him from alien attack. It is Data who shows ordinary human decency rather than rejoicing over Q's misfortune. (Q, when eventually restored, refers to Data as his "professor of the humanities".)
Again and again Data shows these characteristics. Sometimes it leads to him being taken advantage of. In "Legacy" he forms a friendship with Ishara, the sister of his late friend Tasha Yar, and is betrayed. But (in spite of his comments at the end of the episode) he does not close off his willingness to trust.
Data definitely develops in terms of his ability to understand and participate in ordinary social interaction. ("Data's Day" includes some memorable examples.) There are, as for example in "Legacy", some developments in his understanding about the implications of human relations. But are these really the most basic things which define "humanity"?
Let's consider "Pen Pals" again. Data shows compassion. In his development, emotion is always being stressed as the key (which he doesn't have), but as this episode illustrates, compassion and morality are not ultimately matters of emotion (that's not to say emotion isn't involved usually). They're about choices, about how you want to live. J.K. Rowling deals with this very well in the Harry Potter books: Snape is not at all a nice person, but he chooses, in the most important things, to do right. In this sense, Data is human. His desire to be human in the emotional sense is not any less important, of course.
The series finale, "All Good Things", perhaps deals with Data's development best. It showcased Data's development by shifting time periods between the very start, the period of season 7, and a future in which he is a professor at Cambridge. In this future, Data is in many ways the most humane of the characters. The elderly Picard (suffering from a degenerative disease) complains that everyone thinks he is hallucinating. Geordi tries to calm Picard, but Data says, "In all honesty, Captain, the thought has occurred to me." (But he goes on to say that it could be real.) His respectful but honest response is striking. We see this in other interactions too. This highlights, not simply social development, but Data's increased ability to express the humanity that was always there.
Even better, in this future Data is now a mad cat person.