A philosophical zombie is someone who strongly insists behaviorally they are conscious even though they don't actually have any conscious experiences at all. How likely is it that you, the reader, are actually a philosophical zombie?
I am sure that I am not a philosophical zombie -- I have qualia, there is something it is like to be me. The problem is that that is exactly what a philosophical zombie would say, so it's not clear why my saying that should convince you that I am not a philosophical zombie. Unless you don't believe in philosophical zombies anyway. And the concept of a philosophical zombie does seem problematic, in that I appear to rely on my conscious experiences to make such statements as the above, and it seems unlikely that something without conscious experiences could consistently do the same. (Of course, the concept of a philosophical zombie was not introduced to argue that such things are out there, but rather to clarify some of the relevant concepts, for which it is really useful.)