I'm often asked if it's possible to learn how to play guitar using books instead of real lessons. The straightforward answer to this question is, "of course you can". The bigger question is whether or not it's a good idea. This is a little bit harder to answer, but I would say it mostly depends on the style of guitar you want to play. All styles of guitar can be taught by a book, but the more a particular style requires the use of correct posture and hand control, the harder it becomes to teach this way.
All styles of guitar playing require a certain amount of physical discipline. This can include posture, the angle of the wrist, height of the elbow and many other correct practices. However, this is not always so important in, say, Blues or Rock guitar, as it is in Classical or Flamenco. For styles like the latter, it is very important. Even though it's still possible to learn the physical techniques from a guitar book, you would be well advised to use them in conjunction with a tutor to make sure you are using the correct techniques.
Rock and Blues guitar is a little different. Sure, the correct physical techniques can make your guitar playing effortless, faster and more relaxed, but whenever we are faced with this argument, we must always remind ourselves of one important thing - these two genres have been defined predominantly by the self taught guitarist. Some people mistake this for meaning that we actually shouldn't use a teacher if we want to play the blues. This is unfortunately a myth, perpetuated by those with an unwillingness to use logic in their thinking.
The bottom line is this. Using a teacher may or may not make it easier and quicker for you to learn guitar, but it isn't absolutely necessary. The Blues and Rock experts have already proven this. In fact, there is nothing a guitar teacher can tell you that isn't already shown in the books. After all, it's only guitar teachers that write books for teaching you how to play the guitar. So if your teacher says it's a bad idea, ask him if he's ever thought of writing a book for guitar. Damn those crazy hypocrites!
Learning to play from a guitar book obviously has a few drawbacks. For a start you can't ask it questions and it can't tell you if you are doing something wrong. On the other hand, one or two decent guitar books can give you as much information as a teacher could give you in years of expensive lessons. Even if you used a guitar teacher, using books as well is still a sensible thing to do. If money is not a problem then the best compromise would be to use both. The books can give you endless information, while the guitar teacher can tell you whether or not you are applying things correctly.
There are literally thousands of fantastic books available for guitarists, everything from learning the basics to advanced, workbooks, practice schedules, licks, exercises etc., and many of them come with excellent backing tracks on CD for playing along with. You are never too good to gain something useful from them and pick up new ideas, so whether you use a teacher or not, don't let the guitar section of your bookshelf remain empty. Besides, it makes you look cool when your mates come round!