The topics discussed in this book are not a course on formal logic (or symbolic logic). Its aim is to select and discuss several techniques and skills in logic that have a wide application. These techniques and skills can help those who are studying this field to be more critical to distinguish between different matters (or thoughts), debate in a correct and effective manner, analyse and evaluate the arguments of others, identify fallacies in weak arguments, etc. To achieve its aim, this course will pay attention to matters such as the difference between logical possibility and physical possibility (this is because the ability to think and argue logically depends on sound and effective reasoning. This technique does not depend on facts or differences between true or false statements although it may be applicable in fields studying the phenomena existing or occurring in this world including the study of social science, history of mankind and arts), deductive argument known as syllogism, distinguish between valid and invalid syllogism, the use of the Venn diagram as a means to determine the validity of an argument, the difference between validity and truth, modus ponens and modus tollens deductive reasoning, logical relationship between statements (such as relationship that is contrary, contradiction, contradictory, implication, sub-contrary, consistency, etc). In addition, this course also studies the difference between deductive reasoning and inductive reasoning (this is beneficial as certain fields including science and social science use inductive reasoning to support the hypothesis or theory), the difference between necessary conditions and sufficient conditions, how a term or concept is defined, ways to identify the weaknesses of an argument including informal fallacies, ways to challenge and refute weak arguments using opposing examples and counter arguments, the meaning of a dilemma, and many more. Through expounding on these thinking techniques, the course will help students to think critically and effectively.