I agree that having a foundation in raps and scales would definitely be helpful for learning how to walk. But I designed the method to get you started without all the background info. Chapter 1 has nothing to do with scales and arps, it's simply a nuts and bolts way of constructing lines using basic R-5-8 with approach notes. No knowledge of harmony is required, simply target R-5-8 with chromatic, scale, or dominant approach. I realize that it's not as simple as it seems, but in fact all it requires is that you can find the individual notes on your neck. Of course, in 35+ years of teaching one constant I have found is many people don't know their fingerboard well enough to do this right away. So, while I certainly applaud any work you do regarding scales, raps, inversions... to absorb the first half of the book what you need is the basic fingerboard skill of knowing where the notes are (which can certainly be improved with learning scales, etc.).
The second half gets into using scales, arps, chromatic runs... and that is where I start introducing basics of harmony, and it goes much deeper when you get into book 2 (Expanding Walking Bass Lines). But trying to get through Book 1 without knowing your fingerboard will be very frustrating and slow - I've seen it unfold that way many times.
So.... how do you learn your fingerboard you ask? Well, besides all the high quality instruction you can already find for FREE on teh internetz from a plethora of experts....:roll no:
I have an old video on my Bass Whisperer Youtube channel called "Fingerboard Discovery", as well as several lessons on the Bass Emporium website - scroll through the "News" tab and you'll find 11 lessons, many of them dealing with fingerboard awareness through scales, and arps.
Good luck with the book. Be patient. This is not just a musical technique, you are learning a way of thinking and creating music... it's going to be about a year until this stuff becomes part of your fiber.