Unit 1: Logic

Logic Overview

Logic seeks to understand the human activity of reasoning, which can be done well or not so well.  The basic structure of reasoning is the “argument.”  Our goal is to understand if an argument is a “good argument,” that is, an argument that is well reasoned and one we should believe. Our learning will involve:

  • The structure of arguments.
  • Two types of reasoning, deduction and induction.
  • Various types of arguments that use each type of reasoning.
  • Arguments that are defective, that is, arguments with fallacies.

Bad argument (the ones with fallacies) can still be convincing, and we should not be tricked into believing them.

Making good arguments to support your positions on questions and issues is central to “doing philosophy.” So, the Logic unit not only introduces a branch of philosophy but also serves as “training” for doing philosophy.

Learning Objectives

Our work with Logic in this course will equip you to:

  1. Recognize the components of an argument.
  2. Distinguish basic argument types.
  3. Understand what makes an argument either good or defective.
  4. Recognize fallacious arguments and claims.

Coursework

The Logic Unit text is the primary reading material, with links to additional reading or viewing resources.  Subject matter is subdivided as follows:

Section 1.1: Arguments – The Basics
Section 1.2: Arguments – Types of Reasoning
Section 1.3: Arguments – A Few Common Types
Section 1.4: Fallacies – The Basics

Supplemental Enrichment

If you are interested, you may enrich your understanding of basic logic and philosophical argumentation by viewing one or more of the videos or transcripts for Marianne Talbot’s lectures on critical reasoning. [CC-BY-NC-SA]. This activity is optional, and course assessments do not cover material presented by the lecturer unless it is also included in the assigned content of this unit.

Philosophers We Will Meet

In this introduction to Logic, the work of specific philosophers is not addressed, though there have been important and notable logicians over the millennia. In keeping with the custom to be observed in future units where we study specific philosophers’ work, please meet:

Aristotle, who is considered by some to be the the Father of Western Logic.

Key Terms

It is important to understand the meaning and use of these terms.

Argument
A connected series of statements, including at least one premise, intended to demonstrate that another statement, the conclusion, is true.
Cogency
The attribute of an inductive arguments that denotes the truth of its premises and its logical strength.
Conclusion
The statement that is inferred, or reasoned, from a given set of premises.
Deductive Reasoning
Inferential process that supports a conclusion with certainty.
Formal Fallacy
A defect in an argument that can be detected by examining the form of an argument.
Good argument
An argument that is logically strong and has all true premises.
Immediate inference
An argument with a single premise, just one inferential step, supporting its conclusion.
Inductive reasoning
Inferential process providing support strong enough to offer high probability (but not absolute certainty) for the conclusion.
Inductive strength
The attribute of inductive arguments that denotes logical strength. An inductive argument is logically strong when, if all its premises were true, then it’s highly likely or probable that its conclusion would also true.
Inference
The process of basing a conclusion on evidence, or reasoning. The word “inference” may be used to refer to the conclusion/claim itself.
Informal Fallacy
A defect in an argument that can be detected by examining the content of the argument.
Logical strength
The degree of support that the premises, if true, confer on the conclusion. Applies to both deductive and inductive arguments.
Premise
A statement that provides reasons or evidence to support an argument’s conclusion.
Soundness
The attribute of a deductive argument that denotes both the truth of its premises and its logical strength.
Validity
The attribute of deductive arguments that denotes logical strength. A deductive argument is valid when, if all its premises were true, then its conclusion must be true, by necessity.

 

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Introduction to Philosophy Copyright © 2024 by Kathy Eldred is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.