Neither does feminism**. Neither does capitalism. These -isms are what people call 'a philosophy.' Sam has a Marxist philosophy, which undermines her brothers capitalist philosophy, although they still manage to maintain a coherent feminist philosophy when going fishing on Sunday.
I do not fully understand these things, as I have not studied them. It is a dark area and I think it will come in time. Here are my thoughts on the matter, but I warn that they are strangely formed as the landscape for me is still dark and I cannot quite make it out.
I study in an analytic tradition, bias. Philosophy students today, I have been told, tend toward "eclectic." That is, like an apartment full of bookshelves where some of the furniture is modern, an old couch, an Art Nouveau lamp, an oak dining table. There is art on the walls but it shows no coherent interest. There are many things, and they are all in close proximity and it makes a sort of sense all put together but it cannot be read at a glance. Eclectic philosophy is taking the parts of each philosopher which are appealing and using them to build. I have been told that there are no more Kantians. I've heard that James R. Brown is a Platonist, but that does not mean he follows a school of philosophy which adheres to Plato, rather he himself has studied Plato and chosen to consider himself in line with enough of Plato's views to be called as such.
Maybe this is why Marxism doesn't taste like philosophy, because we have waged war on -isms and everything has to be between the person and the book. Maybe it is simply not what I am used to. People also call such things 'ideologies', which refers to ideas that relate to economy and politics. This seems more accurate. Do I delude myself in believing that philosophy is not ideological? No, it is, but there is a difference here. I suppose it is that, like the apartment full of books, it is not obvious what that ideology is, two different ideologies might exist simultaneously and contradict each other and that does not undermine philosophy because philosophy aims at knowledge, not just system. It isn't just a way of doing things.
That is why Ayn Rand is not philosophy. Ideology does not give you breathing room. It tells you what your values are, instead of asking. It dictates all further choices you make. Novels take you near the truth of things, but sometimes the writer is just as puzzled as to why Sam goes fishing with her brother every Sunday as I am. Ayn Rand does not leave any mysteries. There is nothing secret for her, there is no core that cannot be fathomed.
And that is it. It is not modern analytic philosophy only, but also my belief in mystery that leads me to think Marxism is not philosophy. In philosophy there are questions which may not have answers. Sam's brother, who is a very clever person and has many degrees, could spend his entire life arguing that chairs are chairs because we call them chairs and not because of their essential nature. He could make a very important contribution, and Sam would certainly be very proud to have such a clever brother, but it would not settle the problem. It might settle a new area of scientific study, but it would not prevent some other brother the next day or ten years later from writing something just as certain on the other side of the conversation.
Ideologies seem so certain. You learn the system. You look at the world and see the system in it. The system is confirmed and you proceed to take down the feudal system, cut taxes, divorce your lover. These are useful tools. But I do not quite understand how they are philosophy.
**Feminism, not feminist philosophy.