In the beginning of my series on knowledge, I claimed that we need to know what knowledge is in order to know whether or not we have it. Now that I have outlined the basics of the sciences and the various ways that knowledge can be understood, there is enough information to answer that question. What counts as knowledge depends on which science that knowledge is a part of.
When we consider knowledge, we may be inclined to say that knowledge is justified, true belief. As I have shown, this is not the highest form of knowledge and therefore does not count as what knowledge really is. The highest form of knowledge is theoretical knowledge and all other knowledge is knowledge insofar as it is theoretical knowledge. But theoretical knowledge is not of one kind. There are many kinds of theoretical knowledge. If theoretical knowledge had a single definition, then it would all be of one kind. Since it is not of one kind, theoretical knowledge lacks a single definition. But each division of theoretical knowledge is of a single kind. Therefore, each division of theoretical knowledge has its own definition.
This is not the only reason to believe that what counts as knowledge is different depending on which science that knowledge is a part of. Things that exist can be spoken of in various ways. But as I have shown, there is no genus that covers things in all of these aspects. Therefore, there can be no common definition of everything that exists. Since our knowledge of things is related to which things exist, divisions of being imply divisions of knowledge as well. Since math is about quantity and natural science is about material substances, and those have no common definition, knowledge of one will be a different thing than knowledge of the other.
There is one final consideration. Apart from theoretical sciences, there are also productive sciences and active sciences. Just as we have knowledge of theoretical sciences, we also have knowledge of productive and active sciences. Remember that knowledge is knowledge insofar as that knowledge is similar to theoretical science. So we can still have knowledge of both active and productive sciences because those sciences do have knowledge that is similar to the knowledge found in the theoretical sciences.
I will finish this series by briefly discussing each of the theoretical sciences beginning with theology and ending with history.