Welcome to Think Again: How to Reason Deductively! This course is the second in the specialization Introduction to Logic and Critical Thinking, based on our original Coursera course titled Think Again: How to Reason and Argue. We are excited that you are taking this course, and we hope that you will stick around for all four courses in the series, because there is a great deal of important material to learn.In the series as a whole, you will learn how to evaluate deductive arguments. What is it for a deductive to be “valid”? And how can you tell the difference between deductive arguments that are valid and those that aren’t? In this course, we will answer these questions. The first part of this course introduces the series and the course. It also clarifies some peculiarities you may find with this course. We encourage you to watch the "Introduction to the Specialization" video first as it will help you learn more from the materials that come later.

This module we will teach you how such phrases as “and”, “or”, “if”, and “not” can work to guarantee the validity or invalidity of the deductive arguments in which they occur. It will also teach you to understand the functioning of these phrases using a device called a “truth-table”, which shows how the truth or falsity of propositions that use these phrases depends upon the truth or falsity of the propositions contained within it. We highly recommend that you practice the skills that you will learn in this module by doing the puzzles at betapuzzle.sonjara.com. If you want more examples or more detailed discussions of these topics, we recommend Understanding Arguments, Ninth Edition, Chapter 6.

This module will teach you how such phrases as “all”, “some”, and “none” can work to guarantee the validity or invalidity of the deductive arguments in which they occur. It will also teach you to understand the functioning of these phrases using a device called a “Venn Diagram”, which shows how the truth or falsity of propositions that use these phrases depends upon the truth or falsity of other propositions that use these phrases. We highly recommend that you practice the skills that you will learn in this module by doing the puzzles at http://philgames-neta.apps.unc.edu. If you want more examples or more detailed discussions of these topics, we recommend Understanding Arguments, Ninth Edition, Chapter 7.

In this module, we will teach you how to use the tools that you’ve learned about in the preceding modules in order to represent information. Information can be communicated in very different ways – by means of different languages or signaling systems – but no matter how that information is communicated, it can be important to use that information in reasoning. In this module, you will learn how to reason from information that is communicated directly by means of truth-tables or Venn Diagrams.

This module gives you time to catch up and review, because we realize that the previous modules include a great deal of challenging material. It will also be provide enough time to take the final quiz as often as you want, with different questions each time. We explain the answers in each exam so that you can learn more and do better when you try the exam again. You may take the quiz as many times as you want in order to learn more and do better, with different questions each time. You will be able to retake the quiz three times every eight hours. You might not need to take more than one version of the exam if you do well enough on your first try. That is up to you. However many versions you take, we hope that all of the exams will provide additional learning experiences.