Rowbotham does have a point. Since as terrestestial investigators we don't know enough about the moon to say what it is, what shape it might be, or what it is made out of, the author makes a good point that we are assuming a lot with our most basic assumptions.
As an example, depending on skewed view, vertical perspective flipping, or other effects, a lunar pothole could easily be interpreted to be a lunar pimple.
Rowbotham is not expressing the above in particular in his work, but it shows the fallacy of assumption.
Since ICST brought up the idea of projections, another chapter of interest is Moon Transparent.
We could almost forgive Rowbotham for making such claims. The telescopes of his day may not have been as powerful or as abundant as ours are now. Let us not make any conjectures, but look simply at the evidence before us and judge fairly what it is we see. We'll be careful to note every detail, and see if we cannot determine whether we are looking at a pimple or a crater.
I do not wish to debate an issue with you as if we were opposing lawyers. Let's try to remain objective. Here's an image to start with:
This appears at first glance to be a sphere illuminated from the left. Or it could be a bowl lit from the right. What other shapes should we consider? I'll leave that to you to answer while I look closer to test my first 2 hypotheses.
If we look at these "craters" on the left side of the image, we see a clear pattern to them. They are ellipses that are bright on their right edges and dark on their left. As we move from right to left across the image, I see a definite trend that the dark areas of these "craters" grow longer stretching farther to the right.
Next I notice that to the right side of each "crater" past the bright patch, we start to see an extended dark patch. This looks like a shadow.
Could these be pimples? If these are pimples rather than craters, then the moon is lit from the right. That would mean the entire moon is lit from the right, in which case our first guess of its shape was backwards. It would have to be an inside-out sphere - a bowl.
So let's consider the "bowl" hypothesis. My first thought is that is inconsistent with the phases of the moon. We see the phases going all the way from new moon to full moon and back. Can a bowl do that? Isn't there going to be a point where we see the edges of the bowl? I think that's enough to reject the "bowl" hypothesis.
I'm left with the sphere hypothesis, and that makes these craters.
If you can contribute to this objectively, please jump in. What else can we deduce from images like these?