The teaching of metaphysics is meant first and foremost to develop in the student's mind a living habit of thinking ... The presentation of its subject matter in a text for college use should therefore keep that purpose unswervingly in view. Metaphysics is primarily a vital quality or activity of the intellect, and not a collection or systematic organization of data either in print or in the memory. In its own nature metaphysics exists only in intellects, and not in books or writings, though the name may be used, in a secondary sense, to denote a body of truths known through the metaphysical habitus, and to designate a treatise or a course in which metaphysical thinking is communicated.
I agree completely. Philosophy is an activity, not a set of doctrines or propositions, and to become a philosopher is to develop the habit of performing that activity until it comes easily and naturally. So there's a big difference between "learning philosophy" in the sense of learning what it is that philosophers say, and learning what and how philosophers think. Both are needed, but in general surveys on the one hand and detailed scholarship on the other are aids to philosophizing in providing content to philosophize about, but less helpful for actually learning the habit of philosophizing. How do we do that?
Feser recently implied that I was an academic historian of philosophy. That's not really true, but it is true that I have always approached doing philosophy from a "historical" slant, if that means from the opinion that the best way to learn to philosophize is by reading and thinking through the philosophical classics rather than worrying about what the hip kids in philosophy departments are up to these days. That's why I went through the Great Books program at St John's College (the only undergraduate college I applied to) and the historically-oriented doctoral program of the School of Philosophy at The Catholic University of America (the only graduate program I applied to). At both institutions the best is privileged over the current and the primary over the secondary.
A couple of years ago I taught an undergraduate metaphysics course and spent a lot of time thinking over where the best place to start is for a beginner. Books like Feser's or Owens' can be quite useful and I've learned a lot from them, especially when I was a newbie. But they tend to give you information about what metaphysics concerns rather than help you learn to do what metaphysicians do. In the course I designed I wasn't able to do everything I would like, considering the limits of a semester and the average undergraduate. To someone really serious about learning to do metaphysics, this is the advice I would give:
1. Read Plato. Philosophy begins with Plato. After two and half thousand years no one has written better introductory texts: he's the Euclid of philosophy. Everybody should already know this, but it can't be emphasized enough. Autobiographically, my appetite for philosophy was whetted by C.S. Lewis' apologetic works, but I was lucky enough to start reading philosophy at the age of fourteen with the Britannica Great Books volume of Jowett's translations of Plato. Professor Digory Kirke would have approved, I think. Don't read a contemporary "Introduction", which are legion, read The Apology, The Republic, and the Phaedo. Get confused and excited. For methodology read Meno.
2. Now you're ready to start thinking about metaphysics. Sorry: read more Plato. Now it's time to step it up. Read more carefully this time. Think really really hard about what's going on. Try to figure out exactly what the problems are. Read the Trilogy: Theaetetus, then Sophist, then Statesman. You're going to be really and truly baffled, but if you have the makings of a metaphysician your bafflement will have a bracing, exhilarating quality. You're not used to the altitude and can't breathe very well but you can see the stars more clearly than ever before.
3. Read Parmenides and despair. Go back to Sophist and it will seem not so bad, or try something like Protagoras as palate cleanser. You haven't even read the word "metaphysics" yet, but you're confused and worried about being, and a lot of other stuff. You're ready for Aristotle.
4. Any Aristotle you read will be good for you. Maybe read the Ethics first, since it's not so hard and might get you used to thinking in his groove. But you need to read the Metaphysics. It will be very hard and confusing, but you'll start to understand Plato better and also start to understand reality better. I promise.
5. It's time for something different. The Greeks are an indispensable starting point, but you need to move on. You're not trying to become a scholar or a historian, after all. Greek philosophy is the foundation upon which good metaphysics is built, but it remains the foundation. Now, Aquinas. What I recommend is not one of the many decent Thomistic introductions to Thomistic thought, but this book, which is an anthology of texts from all over Aquinas, arranged systematically. I read this book over Christmas break of my freshman year in college, and it blew my mind. All at once the world seemed to make sense. This is what it feels like to move from aporiai to having answers. For all our complaints about "Thomism" here on The Smithy, Aquinas' metaphysics is a beautiful thing. It's also the easiest to learn of all the scholastic metaphysics. This modest 100-page book will be more difficult than many longer modern introductions, but it's all meat, not milk. Do you want to be a little wimpy-mind, or do you want to be STRONG?
Interlude. Think about that last question. If you want to be a little wimpy-mind but still think about philosophy, you have many options. There are lots of ways to "transcend" western metaphysics and feel superior about it without having to do any more hard thinking than what you've done so far. If you want to stay weak but imagine that you're strong, I suggest Nietzsche as your best option. If you want to BE strong, recognize that the hard work starts now.
6. Read Aquinas' Commentary on Aristotle's Metaphysics . This, more than any other book that I know of in English, will give you the metaphysical habit that Owens mentioned in my quote at the top. As far as I'm concerned it's the best metaphysics textbook ever written, bar none. I've read through the whole thing three times, twice in English and once in Latin. I'll read it again. This is not a short or an easy book. However, the difficulties you had in reading through Aristotle the first time will start to clarify themselves. You'll finally start to get a handle on what you've been doing the whole time. You'll start to realize that metaphysical knowledge is possible, not merely questioning and confusion; even if at first it seems like the only thing uou can really be sure about is the principle of non-contradiction. Seriously, this book is a masterpiece and you should read it right now. Take it slow and let it really sink in.
7. Hume roused Kant from his dogmatic slumbers. When you read Plato, then Aristotle, then Aquinas, you felt that you were truly awake for the first time. Dicker around with Thomism as much as you like but eventually you need to realize that you've only reached the stage of lucid dreaming. Thomistic clarity is much better than, say, Cartesian clarity, but it is to a certain extent still an illusion. The Thomist synthesis is brilliant. It's better than any modern philosophy. But it is, alas, in some ways superficial and the shiny veneer of Aquinas' pedagogy papers over some serious cracks. To a certain extent the masonry in his marvelous cathedral of thought is trompe l'oeil where the marble and brick should be. It's not easy to see this at first and the longer you get used to living in the cathedral and admiring the buttresses and stained glass windows the less you want to notice. But it's time for a kick in the teeth. Suck it up and get hold of Scotus' Questions on the Metaphysics of Aristotle. Try to read it. I dare you. This version of part of it will help to some extent, but not as much as you'd like. I'm warning you, this book is not like Aquinas' commentary. Like Aquinas', it's one of the greatest books on metaphysics ever written. Unlike Aquinas', it is fiendishly, fiendishly difficult and, if you really think through it, will destroy your comfortable certainty that you've achieved a basic grasp on metaphysical issues, not through a rejection of the platonic and aristotelian and scholastic foundations you've built up, but from inside them. Figuring out what Scotus thinks is hard; figuring out if he right is harder. There should be many points at which you feel like you're back in the Apology, realizing that all you know is that you know nothing: with the consolation that now at least you have a better idea of what you don't know.
But. If you've really worked through Scotus' book, you will probably no longer be a comfortable naive Thomist (though of course you might remain a Thomist of some sort); you might not be a Scotist either; nobody could call you a straightforward platonist or aristotelian; but I guarantee that by now you've started to be a metaphysician.