1 Foundations of Critical Thinking
Learn how to identify arguments, assess their premises and assumptions, and judge whether their support justifies a conclusion.
What involves
is the deliberate use of clear, reflective reasoning to decide what to believe or do. It requires examining reasons and evidence, drawing and evaluating inferences, and being willing to revise a judgment when its support is weak.
It is not simply skepticism, arguing, or collecting facts. Information becomes useful to a judgment when we assess what it shows and how well it supports a . Start by identifying the question at issue, clarifying important terms, and separating what is known from what is inferred.
Standards for evaluating reasoning
A useful set of intellectual standards helps evaluate claims and arguments. Apply these standards to the reasoning as a whole, rather than only to isolated sentences.
Clarity: Is the claim understandable, and are its key terms explained?
Accuracy: Is the claim true, and how could it be checked?
Precision: Is the claim specific enough for the question?
Relevance: Does the information actually bear on the ?
Depth: Does the reasoning address important complexities?
Breadth: Have significant alternative perspectives been considered?
Logic: Do the reasons fit together, and does the follow from them?
Fairness: Are relevant views and evidence represented without distortion?
These standards work together. A statement can be clear and precise yet inaccurate; evidence can be accurate yet irrelevant; and an can be logical in form but rest on a false . Good reasoning requires suitable support and careful connections between that support and the .
Arguments, premises, and conclusions
An is a set of statements in which one or more premises are offered as reasons for a . The is the point being supported; premises are the reasons or evidence offered in its favor. An makes an inference from support to a claim, so it is different from a mere disagreement or a list of related facts.
For example, a school survey finds that many students cannot use the library before school, and staff are available to supervise an additional morning hour. These premises support the that the school should open the library earlier. The survey provides evidence of a need, while staff availability provides a practical reason. An unstated might be that opening earlier is an effective and worthwhile way to address students’ needs.
Arguments can include subarguments. Evidence that students lack a quiet place to study could support an intermediate claim that library access matters. That claim, combined with evidence about staffing and cost, could then support a recommendation about opening hours. Mapping these steps can make gaps in the reasoning easier to see.
To analyze an , locate its main and then list the reasons offered for it. Words such as because, since, and given that often introduce premises; therefore, so, and thus often signal a . These are clues, not rules: arguments may use other wording or leave the unstated.
Finding assumptions
An is an idea that a line of reasoning relies on, whether or not it is stated. For example, the claim “The library should stay open later because many students study after school” assumes that later hours are feasible and would help meet students’ needs.
Identifying assumptions matters because they can supply unstated links between premises and a . Making them visible allows you to test whether they are reasonable and whether the stated reasons actually support the claim.
How premises support conclusions
Arguments can aim for different degrees of support. A presents its premises as guaranteeing its . It is if it is impossible for all the premises to be true while the is false. It is if it is and its premises are in fact true.
An uses evidence to make a more likely without guaranteeing it. Its strength depends on how well the evidence supports the ; for example, a survey’s value as evidence depends in part on whether it represents the population it describes.
This distinction prevents treating every well-supported as certain. A establishes its if its premises are true. A strong makes its reasonable to accept while leaving room for exceptions or new evidence.
A practical check
Use these questions to assess an :
What exactly is the ?
What premises and evidence support it?
What assumptions connect those reasons to the ?
Are the premises credible, accurate, and relevant?
Do the premises provide enough support for the , given whether the is deductive or inductive?
Have important complications or alternative perspectives been overlooked?
The goal is not to reject claims automatically. Proportion confidence to the quality of the support, and remain open to correction when better evidence or a stronger appears.