How is ‘comparing’ and ‘contrasting’ important in critical thinking?

Short Answer:

Comparing and contrasting is the process of looking at similarities and differences in order to reveal important characteristics of two objects, systems, organizations, events, processes or concepts. In comparing and contrasting two subjects, we  

(i) identify relevant factors for comparison,  

(ii) discuss both similarities and differences between the two subjects with respect to each of these factors,  

(iii) investigate if there are any patterns in the similarities and differences, and  

(iv) make a conclusion based on this investigation.

Long Answer:

Comparison can be seen anywhere and everywhere in nature. In fact, this is a characteristic that can be seen in any animal. For example, the bats recognize the proximity of an object by comparing the distance of the sound reflected from it. All animals can sense their environments in one or more ways. In the case of dogs, they can sense with the help of smell and they differentiate things with the help of this sense of smell. Thus, in some way or another all the organism in the world tends to look for similarities or differences in the surrounding. As human beings we generally have a tendency to compare whatever we see. This comes to us automatically. You can improve your way of comparing things and get an idea of what others are thinking, as everyone has the habit of making comparison knowingly or unknowingly. It helps you to have a better understanding of things in life. 

COMPARING To compare in simple words mean to find the similarities and differences in two things with respect to a certain characteristic that is common to both. For example when you compare an internal examination with a university exam you can clearly understand how they are different and how they are similar. Comparison (noun), when you compare two things you can find out the similarities and differences whereas to contrast means looking only for differences. The word Comparing has a broader perspective as it looks at both similarities and differences whereas in contrasting you look at the differences alone. In the above example of the internal exams and university exams, when compared we can see that the internal exams are of a short duration whereas the university exams are of a longer duration. The number of chapters considered for the internal exams are lesser when compared to the university exam s. Both the exams are necessary to evaluate the knowledge level of the students. In fact, the internal exams prepare you to face the university exams. We usually compare things in order to get some useful information. It is only when the teacher compares two students that she is able to evaluate who is brilliant and who needs help. You cannot compare two things that are very different, and it is difficult to find any similarities between them. For instance two students belonging to two different age groups cannot be evaluated with the same test. However you may find differences among these two students. One student may be capable of answering assertion and reason type question where as the other might be good in comprehension passage type question. But the question used to evaluate them must be set taking into consideration their age. A kindergarten student cannot be evaluated along with a high school student, but you can point out the differences. Hence comparison can be made between any two things taking into consideration some aspect which is similar or different to both the things. 

CONTRAST To contrast means to point out differences between two things. For example the teacher contrasted the formal letter with the informal by elaborating on the style. Contrast (noun) is the difference between two things . E.g.: The contrast between the two books was so evident even though they were written by the same author. Contrasting is a narrower activity than comparing, because you are only considering differences. For example in an elocution competition the judgment is based on the performance of the student who talks better than the other two students. Student A who won the first prize had fluency and matter in her speech where as student B had matter but lesser command on the language. The above mentioned description focuses only on the difference between the two participants and not their similarities.