Because not all persuasive arguments utilize logic to support their assertions, they are not all legitimate. Deductive arguments, on the other hand, can be invalid if the premise and conclusion do not make sense. One example is that all fish swim. I'm a good swimmer. Therefore, I am a fish.
In addition, some arguments depend on emotion or subjective opinion for their validity. An argument based on emotion is said to be emotional. An argument based on preference is said to be subjective. All emotional arguments are not equal: Some are very powerful, while others are not so much. Subjective opinions may also vary in strength; one person's favorite color is another person's nightmare. There is no way to determine how strong an opinion is until it is expressed, so keep this in mind when evaluating arguments.
Finally, some arguments are fallacious because of where they go wrong. A logical fallacy is any mistake made during argumentation that causes us to believe what we were trying to disprove. Common mistakes include arguing in circles, assuming what you're trying to prove, and misrepresenting your opponent's position.
All logical arguments are not created equal. Some are more effective than others at convincing someone of their point of view. How do we know which ones are which? That's what we'll discuss next time.
A deductive argument is considered to be valid if and only if it is written in such a way that it is impossible for the premises to be true while the conclusion remains false. A deductive argument is considered to be invalid if it is not supported by evidence. An inductive argument is considered to be valid if and only if it tends to produce conclusions that are true in the world around us.
A deductive argument uses logic to show how certain conclusions must follow from certain premises. These arguments can be divided up into two main types: logical arguments and mathematical arguments. In a logical argument, the conclusion must be true no matter what facts are assumed as premises; for example, "All dogs are mortal; therefore, Socrates is dead." In a mathematical argument, on the other hand, the conclusion depends on the truth of certain facts which may or may not be stated as assumptions. For example, "The population of Earth is increasing; therefore, we need more food than before." Logical arguments are used in science because scientists want to know whether their theories are correct. They use logical arguments to prove that their theories are accurate descriptions of reality. For example, scientists use logical arguments to prove that their theories of evolution by natural selection are accurate accounts of how species evolve over time.
Inductive arguments are tools used by humans to make predictions about the future.
In effect, an argument is valid if the truth of the premises assures the truth of the conclusion logically. For example, suppose we were to argue: all bachelors are unmarried men; John is a bachelor; therefore, John is unwed.
This argument is considered valid because the truth of the first two statements implies the third. There are several other common types of arguments in philosophy, including inductive, abductive, and probabilistic arguments. Inductive arguments show that something is true because it has been found to be true in many cases. For example, we might argue that all bachelors are unmarried men because there have been so many cases where this has been found to be true. Abductive arguments show that something is true because it is the only thing that can explain some facts about the world. For example, we might argue that all bachelors are unmarried men because nobody else could possibly be responsible for all these marriages. Probabilistic arguments show that something is likely true because it has been found to be true a lot of times before. For example, we might argue that all bachelors are unmarried men because statistics show that most people who are married are not widowers.
All valid arguments attempt to prove or disprove a hypothesis.
All valid arguments start with truthful premises and end with true conclusions. A good argument must have at least one true premise. Every sound argument is a legitimate argument. A good deductive argument is as follows: If it snows, we'll go sledding, just like we did when we were kids. Therefore, it will snow today. This argument is sound because each step is justified by the one before it. It doesn't matter what else happens, as long as it doesn't disprove the conclusion.
Analogous reasoning applies to inductive arguments. If we know that dogs make good pets because they have been trained to do things for their owners, then it makes sense that Samson would be a good pet since he has been trained to protect his owner. Although we can't prove this theory by writing a book on the subject, it does not matter what other possibilities may exist, as long as they don't contradict our conclusion.
Arguments can be classified as simple or complex. A simple argument states a single conclusion based on single premises. Because there is only one possible outcome (this goose is white) no matter how many times you repeat the experiment, there is only one way it could have turned out. In contrast, a complex argument includes several lines of reasoning and various forms of evidence that lead up to one conclusive result.