I'm a sucker for a solidly-written pedagogical textbook, and this one may be my favorite. Philosophy makes for a tedious read, but Christian writes lucidly, as well as elucidately, about the breadth of thought, whether you choose to call that thought philosophy or something less intimidating such as logic or rational thinking or even rationalization.
I regret that all the editions of this book are separated here on goodreads, but in the end, splitting reviews isn't going to affect sales or buzz for a college text. Also, I have read only this edition, so any changes are beyond my cognomen, you might say, so perhaps splitting them into discrete books is the right approach for this book.
This is--by far--my preferred èntre to the amorphous human activity of thinking beyond, throughout, within and beneath the moment. Also, one of my favorite books ever.
I should read a more recent edition. I could use a booster shot of fine thinking about thinking.