Uncovering Implicit Premises
Reasoners often leave parts of their reasoning unstated. Emilio left something unsaid when he argued that “If the stream were poisonous, everything in it would look dead. There are water spiders and plants in...
Deductively Valid and Inductively Strong
The primary goal in argumentation is for the conclusion to follow from its basic premises either with certainty or with high probability. Technically, this means the arguer desires the argument to be deductively valid...
Rewriting Arguments in Standard Form
Can you spot the conclusion and premises in this argument? All machines have a finite working lifetime, and even though that big tree doesn’t look like a typical machine it is really just a...
Discount Indicators
It is very common for passages containing arguments also to contain claims that are neither premises nor conclusions but instead send a signal that another claimed should be de-emphasized or discounted. Here’s an example...
What is a Proof?
People often argue in order to prove something. But that word “proof” is a tricky word. There are different standards of proof in different situations. You have to meet a higher standard if you...
What is the Issue?
We argue in order to settle issues. Issues arise when there is uncertainty about whether to accept or reject a claim, or about what to do or not do. For example, someone argues for...
What is an Word Argument?
The word argument has more than one meaning. In this book we will not use the word in the sense of being unpleasantly argumentative. Instead, it will mean at least one conclusion supported by...
What is a Statement?
Statements are what is said. More accurate, statements are things that are said that are either true or false. They are also called claims. Here is one: “Neptune has the fastest winds in the...
Review of Major Points
This chapter emphasized that logical reasoning is your guide to good decisions. It is also a guide to sorting out truth from falsehood. This chapter began with several case studies of logical reasoning. It...
Examples of Good Reasoning
So far we’ve explored the importance of reasoning logically in situations that require a decision—either a decision about what to do or a decision about what to believe. Along the way we’ve introduced a...
Facing a Decision as a Critical Thinker
Imagine this situation. You are on a four-day backpacking trip in a national wilderness area with your friends Juanita and Emilio. The summer weather’s great, the scenery is exotic, and you’ve been having a...
