PHIL 336 PART 2

8/16/22, 3:08 PM Reading 2.1: What is Logic, Proposition, Argument? - PHIL 336 6380 Ideas Shaping the 21st Century (2228)

https://learn.umgc.edu/d2l/le/content/717197/viewContent/26959984/View 1/2

What Is Logic, Proposition, Argument?

What you will learn in this reading

What the object of the study of logic is What the definition of a proposition is What the definition of an argument is What conclusions and premises are

In Logic, the object of study is reasoning. This is an activity that humans engage in—when we make claims and back them up with reasons, or when we make inferences about what follows from a set of statements.

Like many human activities, reasoning can be done well, or it can be done badly. The goal of logic is to distinguish good reasoning from bad. Good reasoning is not necessarily effective reasoning; in fact, as we shall see, bad reasoning is pervasive and often extremely effective—in the sense that people are often persuaded by it. In Logic, the standard of goodness is not effectiveness in the sense of persuasiveness, but rather correctness according to logical rules.

In logic, we study the rules and techniques that allow us to distinguish good, correct reasoning from bad, incorrect reasoning.

Since there is a variety of different types of reasoning, since it’s possible to develop various methods for evaluating each of those types, and since there are different views on what constitutes correct reasoning, there are many approaches to the logical enterprise. We talk of logic, but also of logics. A logic is just a set of rules and techniques for distinguishing good reasoning from bad. There are many logics; the purpose of this introductory module is to give an overview of some of the most basic ones.

So, the object of study in logic is human reasoning, with the goal of distinguishing the good from the bad. It is important to note that this approach sets logic apart from an alternative way of studying human reasoning, one more proper to a different discipline: psychology. It is possible to study human reasoning in a merely descriptive mode: to identify common patterns of reasoning and explore their psychological causes, for example. This is not logic. Logic takes up reasoning in a prescriptive mode: it tells how we ought to reason, not merely how we in fact typically do.

Basic Notions: Propositions, Arguments, Conclusions, Premises

Reasoning involves claims or statements—making them and backing them up with reasons, drawing out their consequences. Propositions are the things we claim, state, assert.

Propositions are the kinds of things that can be true or false. They are expressed by declarative sentences. ‘This book is boring’ is a declarative sentence; it expresses the proposition that this book is boring, which is (arguably) true.

Other kinds of sentences do not express propositions. Imperative sentences issue commands: ‘Sit down and shut up’ is an imperative sentence; it doesn’t make a claim, express something that might be true or false; either it’s obeyed or it isn’t. Interrogative sentences ask questions: ‘Who will win the World Cup this year?’ is an interrogative sentence; it does not assert anything that might be true or false either.

Only declarative sentences express propositions, and so they are the only kinds of sentences we will deal with at this stage of the study of logic. (More advanced logics have been developed to deal with imperatives and questions, but we won’t look at those in an introductory module.)

8/16/22, 3:08 PM Reading 2.1: What is Logic, Proposition, Argument? - PHIL 336 6380 Ideas Shaping the 21st Century (2228)

https://learn.umgc.edu/d2l/le/content/717197/viewContent/26959984/View 2/2

The fundamental unit of reasoning is the argument. In logic, by ‘argument’ we don’t mean a disagreement, a shouting match; rather, we define the term precisely:

Argument = a set of propositions, one of which, the conclusion, is (supposed to be) supported by the others, the premises.

If we’re reasoning by making claims and backing them up with reasons, then the claim that’s being backed up is the conclusion of an argument; the reasons given to support it are the argument’s premises. If we’re reasoning by drawing an inference from a set of statements, then the inference we draw is the conclusion of an argument, and the statements from which its drawn are the premises.

We include the parenthetical hedge—“supposed to be”—in the definition to make room for bad arguments. Remember, in Logic, we’re evaluating reasoning. Arguments can be good or bad, logically correct or incorrect. A bad argument, very roughly speaking, is one where the premises fail to support the conclusion; a good argument’s premises actually do support the conclusion.

To support the conclusion means, again very roughly, to give one good reasons for believing it.

This highlights the rhetorical purpose of arguments: we use arguments when we’re disputing controversial issues; they aim to persuade people, to convince them to believe their conclusion. As we said, in logic, we don’t judge arguments based on whether or not they succeed in this goal— there are logically bad arguments that are nevertheless quite persuasive. Rather, the logical enterprise is to identify the kinds of reasons that ought to be persuasive (even if they sometimes aren’t).

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Source: Knachel, Matthew, “The Basics of Logical Analysis.” Fundamental Methods of Logic. UWM Digital Commons (2017), Chapter 1, pp 1-3. (CC BY)