ABSTRACT
An introduction of the concepts of validity and soundness, the main concepts required for the analysis and assessment of deductive arguments. These are arguments whose premises, if true, guarantee the truth of the conclusion. We discuss the assessment of validity and soundness, and explain the meaning and use of the principle of charity. We provide a sketch of the connection between critical thinking and symbolic logic, or between informal logic and formal logic, plus a section on the use of Venn diagrams for the logic of the syllogism.
