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Skip to 0 minutes and 1 second Hello and welcome to ‘Logic: the language of truth’. An exploration of the basics of formal logic and how it can be used as a tool to clarify and evaluate arguments expressed in everyday language. My name is Tom Stoneham and I’m Professor of Philosophy and head of department at the University of York. I will be leading this course with my colleague, Dr Barry Lee, and some of our students at York. This week we will begin by looking at reasoning.

Skip to 0 minutes and 32 seconds We all have an interest in working out what to believe; we’re often faced with people trying to get us to believe something by making a case for it, by giving an argument for it, in the sense of laying out some claims, which are meant to support their conclusion. Sometimes we also want to do that ourselves; we want to persuade others to believe a conclusion by laying out some claims, our ‘premises’ which are meant to support it and sometimes we just want to figure out what to believe by seeing what follows from things we already know. In all of these cases, it’s important to know when the reasoning is good.

Skip to 1 minute and 5 seconds What really follows from what; when there really is a positive connection between the truth of those starting claims (the premises) and the alleged conclusion.This week, we will look at the basics of reasoning and get some key ideas in place. A lot of this will involve giving definitions of familiar terms so that when we use them, we’ll know exactly which concept is being expressed. I just talked about ‘claims’ and how some are premises and others conclusions. We’ll define a ‘claim’ in a way that relates sentences and truth, then we’ll define ‘premise’, ‘conclusion’ and ‘argument’. This way we will gain a sharp understanding of what our subject matter is when we’re doing formal logic.

Skip to 1 minute and 48 seconds Then, we’ll introduce the key idea that will be the focus of our work throughout the

Skip to 1 minute and 54 seconds module: ‘deductive validity’. This is the technical concept of the positive relation we seek between the claims which are offered as premises and the conclusion that follows. We’ll see how focusing on deductive validity can give us an important route into a systematic and objective understanding of good and bad reasoning.

Introduction to the course by Professor Tom Stoneham

Professor Tom Stoneham, Head of the Philosophy Department at the University of York, introduces you to the course.

Each week we will be introducing you to a different aspect of formal logic and its application to claims and arguments expressed in everyday language.

Week 1: Bringing Logic Into Focus

In the first week we will begin by looking at the idea of an argument, introducing the key concept of deductive validity, and taking a first look at logical form.

Week 2: Formal Languages and Natural Languages

This week we start to build our logical language by defining its first sentence-connective, we introduce a key tool—the truth-table—and start to explore relationships between our logical language and everyday (or natural) language.

Week 3: Complex Sentences and Logical Properties

This week we expand our logical language and look at how to tackle complex sentences. We see how we can clarify claims by avoiding a key kind of ambiguity. We explore how to test for key logical properties and relationships.

Week 4: Testing for Validity

In the final week we add our final and most controversial sentence-connective and explore its relation to connectives in English. We see how to test for validity, and we apply what we’ve developed to some more complex arguments.

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This video is from the free online course:

Logic: The Language of Truth

University of York