Books? I think that would be an ineffective way to get into reading philosophy for the MCAT unless you were planning to read several of them over a long period of time. The challenge of the verbal section is to outline the important concepts in your head into a way you understand, and to do it efficiently. Reading full-length philosophical works will only help you learn many details about the same topic. Pick up the TPR Hyperlearning book and do the philosophy passages. For the first few you pick, give yourself unlimited time and do an outline of the ideas presented BEFORE you answer the questions. Try to answer them without looking back to the passage. When you get good at this, shorten allotted time and the amount of things that your write until you're able to do them quickly without any writing! 7-8 is no bueno and shows that you need to improve your overall strategy. You may get boned on test day if there's only one philosophical passage, so it's best to prepare for everything.
If you'd a book that's full of passages that would make people poop their pants if they came up on an MCAT, try The Metaphysics of Morals. You Kant go wrong with that. The writing style and organization is also pretty conducive to pulling them out of context like the MCAT does.
