Understanding a text can lead to evaluation of a text. Once you understand what the author is saying and what you personally think about the text’s message, you can go a step further to consider the text’s value, which is what evaluation does. Although evaluating a text involves asking many questions about it, the result of any evaluation leads to answering one key question: “How well does the text do what it does – what is its value?”  To determine how well the text works, the two main things to investigate are the text’s content and language.
That’s where critical thinking comes in. The “critical” in critical thinking does not mean that you’re finding fault with a text. On the other hand, it does mean that you evaluate a text to see how well it works, in order to decide the worthiness or quality of the author’s ideas. Evaluation is based on objective (not subjective or emotional) criteria: the text’s main idea, the relevance and quality of the evidence supporting that main idea, and how the author presents that main idea. Since so many different things can be defined as text—an email, a television commercial, a blog post, an election campaign platform—in addition to a written article, the ability to evaluate a text is an important transferable skill.
The video below discusses critical thinking within the context of reading.
Critical thinking depends on analysis. According to The American Heritage Dictionary, analysis is “the separation of an intellectual or material whole into its constituents parts for individual study.”  Analytical reading starts with finding and understanding a main idea, but then considers the validity of that main idea by studying its parts, to see how logically they fit together. The parts of a text fall into those two main categories, content and language, and include things such as the author’s main idea, supporting ideas/evidence, purpose, assumptions, point of view, and tone—the devices or tools that authors use. You’ll ask and answer many questions based on the parts of a text, such as the following:
- Is the text’s main idea or assertion reasonable and logical?
- Are there underlying assumptions or perspectives that affect the text’s content and language?
- How does the language influence the way a reader understands the text?
- and more…
For example, if you examine the text of an ad for clothing detergent, you may find that the author an author manipulates language and content to persuade you to accept a certain point of view that may not be fully supported or logically valid. The ad may provide an opinion from a “real” parent, speaking emotionally in a sincere tone, that Brand X gets his kids’ clothes cleaner than other brands. The ad may provide statistics to back up its claim: “four out of five parents prefer Brand X.” Yet how valid and valuable is this content? How believable is the text’s claim? Analyzing the parts of the ad’s text will help you determine its value.
It’s even more important to think critically and analytically to evaluate a text when an author manipulates the parts of a text in a less obvious way, in a magazine article, a political speech, a source for a research paper, or an appeal for funds. As a critical reader, you need to be able to identify the author’s techniques so you can decide whether to accept or question the message in the text. Understanding critically and analytically how a text works will help you determine its value.
 Wording of the evaluation question quoted from Duncan, Jennifer, modified by Michael O’Connor. Reading Critically handout. The Writing Centre, University of Toronto Scarborough. https://www.stetson.edu/other/writing-program/media/CRITICAL%20READING.pdf
 The American Heritage Dictionary. https://ahdictionary.com/word/search.html?q=analysis