"In the English-speaking world the great majority of books that have been published in philosophy in the twentieth century are like academic paintings: they show unmistakable talent and are professionally competent, the result of long processes of learning, application and work; everything in them is accurate, in its right place, and as it should be; but it makes not the slightest difference whether they exist or not."
Bryan Magee --Confessions of a Philosopher
There are a lot of people who agree with Magee that the great and influential works in philosophy were all written before 1900.
Here's an assignment for the philosophy majors out there. Name three technical books written in the twentieth century in the discipline of philosophy which, for better or worse, have made a difference in how we look at the world.