Critical thinking is reasonable, reflective thinking that is aimed at deciding what to believe or what to do (Rober t Ennis, 1987). The detailed explanation is as follow
1. Deciding what to believe
Deciding what to believe is a matter of deciding what the facts are, figuring out what the world is like, or at least what some little corner of it is like. In deciding what to believe on some matter we take a stand on it. If it is a decision on a factual matter, then we take a stand on what the facts are. If it is a decision on an evaluative matter, then in deciding what to believe we are taking a stand on what is good or better . In either kind of case, critical thinking is aimed at helping us to make those kinds of decisions about what to believe.
1. Deciding about what to do
Critical thinking is also aimed at decisions about what to do. Deciding what to do really has two parts. First, one has to decide what to value or to strive for. This is a matter of determining on one's goals or end. Then, one has to decide how best to achieve that end. This is a matter of deciding on the best means to that end.
Critical thinking is reasonable in another and deeper sense. Critical thinking about what to believe or what to do is reasonable in that it demands that we have reasons, and preferably good ones, for making the decisions we do. The aim of critical thinking is not simply to make a decision on what the facts are or what to strive for. In a way, it is easy to make such decisions. What is hard is having good reasons for the decisions we make. It is not enough to decide to believe that it is sunny out ; one has to have good reason to decide this. Likewise, it is not enough just to decide to value honesty or justice; one has to have good reason for this decision. So critical thinking is reasonable in that it demands that we have reasons, and preferably good ones, for making the decisions we do. We will be spending a lot of time in what follows exploring what makes something a good reason to believe or to do something.
Critical thinking is also reflective. Critical thinking is reflective in the sense that it involves thinking about a problem at several different levels or from several different angles all at once, including thinking about what the right method is for answering or solving the problem.
Critical thinking is valuable for two main reasons. First, thinking critically increases our chances of gaining knowledge, and knowledge is valuable. Second, thinking critically is essential to making up one's own mind about what to believe or what to do, which is essential to being autonomous, and being autonomous is valuable.We have seen that critical thinking is thinking that is aimed at deciding what to believe or to do. But ideally we want more than just to have an opinion about the facts; we want to know what they are. So critical thinking is really aimed at knowledge. Facts will be a knowledge unless it is true. Unfortunately true facts is not enough to become our knowledge, we must believe the true facts. The last step to make facts to be knowledge is justification. To say that a belief is justified is to say that it is based or grounded in good reasons, that the believer has adequate or satisfactory reason to hold or to sustain her belief.
Critical thinking is important not only for knowledge but also for autonomy. Thinking critically is essential to making up one's own mind, and this is fundamental to being an autonomous person. By critical thinking you will have the power the power to determine one' s self, to decide on one's own what to do or what to believe, what kind of life to live. Because critical thinking demands reasons and requires us tobe reflective as we decide what to believe and what to do, thinking critically is crucial to exercising our ability to determine our own minds,
Hunter, David A. 2014. A Practical Guide to Critical Thinking: Deciding What to Do and Believe, Second Edition A JOHN WILEY & SONS, INC., PUBLICATION