Every day we are exposed to all sorts of claims. Television, the internet and other forms of mass media barrage us both with advertising and with what purports to be objective reporting of the facts. The same is true of our face to face encounters with family, friends, teachers and random strangers we happen to meet. How should a sensible person respond to all the claims that they hear or read on any given day? To believe everything is clearly not a good idea. We call people who tend to believe everything they hear "gullible." To refuse to believe anything other people say is, if anything, even worse than being gullible. An intelligent person wants to be selective. To sort out and reject the false claims but to hold on to and accept the truthful new information that comes their way. Critical thinking is about being intelligently selective in responding to people's claims.
Psychologists tell us that people tend to be skeptical only of claims coming from people whom they dislike. We tend to believe everything we hear from people we do like. A critical thinker is someone who decides whether or not to believe something based on objective reasons and not on personal likes or dislikes. Accordingly, a critical thinker forms the habit of asking people, friend and foe alike, to back up what they say with reasons. Because people often express themselves in vague language, the critical thinker will also be in the habit of asking questions of clarification to establish what people really mean to say.
When a person gives reasons to back up one of their statements, they have given an argument. Arguments essential consist of an inferential claim: the claim that a reasonable person ought to believe the conclusion if they admit that the premises are true. Inferential claims can be either absolute or probabilistic. These claims can also be evaluated. The critical thinker also possesses the skill necessary to tell whether inferential claims are objectively true or false.
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