Is Philosophy Significant to Anyone Else but a Philosopher?

Yes, I think it is widely significant. There are two main reasons I think this. Firstly, everybody, when they try to think a little more deeply about their beliefs and the assumptions they rest upon (or even better, discuss this with friends) is to that extent a philosopher. And this can have some quite profound effects on people.

Secondly, philosophical ideas produced by 'real philosophers' (whatever they are) can have effects far beyond their recognized reach. It is true that many philosophers are read only by other philosophers — or people who are close to philosophy. The views of these people are affected. They then can write about other matters — political, ethical, whatever, in a way that is affected by the philosophical views they have read. Others read this, and in turn write or speak. In this way, philosophical views spread and influence many facets of our lives.

Let me give some examples. The ideas of John Locke about how to run a state affected the writings of many, notably the American founding fathers. The U.S. Constitution is organized in accordance with them. This has had pretty wide effects, I think you would agree.

Or a couple of others. Immanuel Kant's writings on reason heavily influences the Enlightenment — ideas that progress is inevitable and that objective reasoning leads to better actions. Friedrich Nietzsche's criticisms of this approach have led to a world in which such objective thinking and central planning, based on the belief that there is one right answer to every problem, is now widely mistrusted.

I probably don't need to expand on the influence of Karl Marx — basically a philosopher of sorts — who said famously: "Philosophers have previously interpreted the world. The point, however, is to change it." Anybody who sets out to change the world, however, must first have interpreted it, and although they may not recognize it explicitly, that interpretation is likely to have been influenced by the positions of philosophers.