Put simply, the goal of the Bodybuilder (qua bodybuilder) is to look good. We all know that looking good is a subjective matter, but the bodybuilder believes that to look good one must be muscular and large, at least more muscular than the average person. Exactly how much additional muscle mass is desired is a matter of individual preference.
What is constant for bodybuilders is the desire to increase their mass at least somewhat. Additionally, the cost one is willing to pay in the pursuit of that mass varies quite a bit. Some people are willing to spend a lot of money, endanger their health with drugs and sun exposure, etc., to increase their mass. To be a bodybuilder one must be willing to at least train very hard, the minimal sacrifice required to increase mass.
Both of these things are important to the bodybuilder's quest. I have found that the current literature (both the muscle magazines and the web sites devoted to bodybuilding) tends to ignore the importance of proportional developnent. For those who are interested, there was much more discussion of proportion back in the early 70's in places like Muscleamag International.
There a number of lifestyle variables (things you do every day) which affect both bodyfat and muscular development. I will go into more detail in other postings, but training, diet, sleep, stress, supplementation, and mental attitude all affect both fat levels and muscular growth in different ways. I don't want to make things seem unnecessarily complicated, but optimizing you chances for developing a good body is a complex thing. On the other hand, most people, especially beginners, will grow well without optimizing their internal environment. That is, beginners can get away with quite a bit of suboptimal behavior.
If you have read Mike Mentzer and basically understand him, you can sort of skip this part. He makes many mistakes about the role of logic in epistemology, but we can forgive him that much. I do agree with the general theme of his writings. Most people, perhaps especially bodybuilders, conceptualize mystically. They form their beliefs based on an uncritical acceptance of what they have been told by others.
I have never been satisfied with that method. Not only was my bodybuilding progress unsatisfactory when I used the 12 sets per bodypart system (although I did lose a lot of weight on that system) but I didn't feel as if I understood why I was doing what I was doing, as opposed to some other program. Thanks to Mentzer and quite a bit of my own critical reflection I have come to a much better understanding of the proper way to train, and of the logical support of that method.
Many others who want to learn how to train use principles derived from scientific research to design their programs. While this is a worthwhile endeavor, it makes me suspicious. So many variables in training are hard to control, such as intensity and "feeling" a muscle while working it, that I doubt any worthwhile research has yet been done to show what the best training method is. Some things have been determined, such as optimal set length times and so on. But stay clear of research reporting the benefits of three sets over one - it is unlikely the subjects involved used controlled form, intensity levels, or diets.
What I will do, rather than quoting scientific research articles ad nauseum, is explain why I believe what I do, based on common sense observations and on logical deductions from observable regularities.
If I ever fail to adequately support my claims, feel free to challenge them. If you just think that I'm dead wrong about everything, fine. But don't tell me that unless you can tell me how I'm wrong and why you think that. Hopefully, we can communally work out the truth, and become huge beyond words.