A text or a statement’s value depends on the competence of the author on the subject and is based on the validity and truthfulness of the information. To have the skill to evaluate the sources and the information the author uses, is not an ability, but the result of a long process of getting to know a subject, over time. A wide range of information allows to value and pass judgement objectively on the exposed. On the contrary, any farfetched statement can be taken as truth, or the other way around, it can have not enough power to take a source as valid.
The key point is directly related to the previous post. For an expert reader, it is easy to see the difference between a good text and a great one; a beginner will need to perform a more exhaustive examination on both of the objective and of the sources of the content. We could say that a fact is a piece of information that corresponds with reality, and an opinion constitutes a point of view or interpretation on that reality. We can say an opinion may or may not be true, but it needs elements to sustain it in order to become a fact. Distinguishing facts from opinions is an effective filter to accept or not the author’s ideas.
As it was said, these three conditions are basic for a critical reading; there can be more to be considered, according to the needs or interests of the reader. Anyway, it needs to be considered a competence to develop throughout a life time and that can range from the simpler to the most elaborate critique. The most important point may be reading always with that intention, with that spirit, because, then, we could say that only those who can, not those who want, will be able to critique.