Chapter One:
Basic Concepts of Logic

In this chapter we study many of the fundamental concepts relating to good reasoning. How does evidence support a conclusion in a "valid" way? What is it for premises to make a conclusion likely? When can we reasonably say that two sentences "mean" the same thing?

We'll discover that these basic ideas can be difficult ones, that they may even be philosophically vexing. (Is there really such a thing as good, correct reasoning? And when we say that two sentences mean the same thing, what is this meaning thing?) Thus, this chapter merely introduces the ideas of logic; they require much further elaboration in the later chapters.

Specifically, these later chapters will take the current chapter's ideas and apply them to special, artificial languages that are simpler than English (or other "natural" languages). In this setting, the logical concepts should be clearer.

To begin, we will get a rough idea of what logic is, then make these notions more precise in the coming chapters. Start with the introductory tutorials presented below, then print out the reference manual for this chapter (that way you'll have a concise statement of this chapter's details to refer to even when away from the computer.) Finally, and most importantly, carefully work your way through the chapter exercises.

Tutorials for Chapter One

 1 Start Here: The goals of symbolic logic   — Café Demo 2 Some definitions: Arguments Part I of T2      — Flash: doing 1.2's exercises Validity and Soundness: Part II of T2 3 Possibility, Deductive Logic, Inductive Thinking: Part I of T3 Informal Proofs: Part II of T3 4 Further Concepts of Deductive Logic: Part I of T4 More Informal Proofs: Part II of T4

Exercises for Chapter One

1.1ex I Multiple Choice

1.2ex I Standard Form for Arguments (problems from T1.2)
1.2ex II More Standard Form (some easier problems)
1.2ex III More Arguments to put in standard Form (some a little harder)
1.2ex IV Multiple Choice
1.2ex V Valid Arguments...Dragging

1.3ex I A Drag
1.3ex II Multiple Choice
1.3ex III Informal Proofs

1.4ex I Another Drag
1.4ex II Multiple Choice