Critical thinking is "thinking about thinking". It is a way of deciding if a claim is true, false, or sometimes true and sometimes false, or partly true and partly false.
To find out if someone is telling you the truth, one needs evidence. Information is found in libraries, online, and by asking people. Professional librarians can help research library sources. Cybrarians can help research using computers. Professional interviewers are good at finding people who are experts in their fields, and they know how to ask the right questions.
To solve a problem, questions can be written as clearly and simply as possible, making certain that all terms are well understood by giving definitions if necessary. Then, this critical thinking can help one judge how true this information is. Critical thinking tools are taken from many fields of study: statistics, logistics, semantics, experimental research methodology, psychology, sociology. Research sources should be of good quality: up to date, thorough, well-informed, and impartial.