Ignorance is nothing but the lack of knowledge, but where there nonetheless remains the capacity [or possibility] for knowledge. In animate objects and non-speaking animals cannot be called “ignorant” or “knowledgeable” in any way. Ignorance is like being blind. One is without sight, but a blind being is someone or something that normally would be able to see. As such, we would not call a rock “blind.” The contradictory relationship between “blindness” and “sight” is a kind of opposition of privation and possession. We can say that knowledge and ignorance are based on the presence or absence of a given faculty.
Ignorance has two divisions, insofar as ignorance is always contrasted to knowledge. Sometimes it is reciprocal to an conception and sometimes to an assent. It is correct to use the terms conception-ignorance and assent-ignorance. We can further divide ignorance, and say that there are two kinds: simple ignorance and compound ignorance. In reality, it is only conception-ignorance that can be divided in this fashion, and so we can really only subdivide ignorance into conception-ignorance and assent-ignorance. As far as the conception-ignorance, it is always simple ignorance, as will be discussed.
1) Simple ignorance [jahl baseet]: This is a situation where someone is ignorant about a thing, but he is aware of his ignorance, and knows that he does not know. So we may know that we are ignorant about the motion of Mars; we may not know whether or not Mars is in motion, but at least we know that we don‟t know, and so in reality we only have one kind of ignorance.
2) Compound ignorance [jahl murakab]: This is ignorance about a thing, but combined with ignorance about ones ignorance. Such a person believes that he has knowledge where he does not. In this case, one does not know that one is ignorant. All the people with false beliefs would fall into this category; they believe that they are knowledge about the reality of things, but are ignorant in reality.
We call this compound ignorance because it is actually two kinds of ignorance joined together: ignorance about reality, and ignorance about ignorance. This is the ugliest and most base kind of ignorance. This kind of ignorance can only occur in the realm of assent, since such an ignorance is always accompanied by some kind of belief.