PHIL 2020 Unit 4: Lecture 1 Logic We defined critical thinking as the discipline concerned with evaluating thoughts, or reasoning. Logic is generally concerned with the identification and application of the correct rules of reasoning. Thus, critical thinking presupposes logic. To the extent that you are able to think critically, you already have some intuitive grasp on logic. Formal Logic To come to a higher understanding of logic, however, we need to come up with a way of making the topic more explicit. Formal logic is one way of trying to do this. We have already studied one concept from formal logic this semester Formal Fallacies Argument Form The weakness of formal fallacies can be assessed in which of the two dimensions of argument strength that we have named? Relevance why can this weakness only be assessed in terms of relevance? o Because, if we only look at an arguments form, we have no idea whether the premises area reliable or not. o Exs. If today is Friday, then you have class today. Today is not Friday; therefore, you dont have class today. o If P, then Q. Not P; therefore, not Q. Form and Content How do we decide what counts as form and what counts as content in evaluating an arguments form? The answer is complicated; however, we can start to make this distinction in terms of a concept with which we are already familiar: statements. Simple and Complex Statements For the first logical system we will study, an arguments content will be identical with the simple statement it uses. Call a statement simple if (and only if) it only attributes exactly one predicate to exactly one subject. Call a statement complex is if and only if it is a statement, but not a simple statement. Ex. Socrates is a mortal. Plato and Aristotle are Greeks. For our initial purposes, identifying an arguments form will consist of identifying the simple statements it uses, and the logical grammar in virtue of which its complex statements say what they do. Thus, in our two previous samples, we only need to note that Socrates is a mortal is a simple (or atomic) statement. To understand the form of the second statement, we need to note that the connective term and is used.