#clear_thinking/logic Summary::Deductive Logic provides a way to develop sound conclusions. --- ## Related Topics [[Introducing the Learning Progression]] --- # References Language & Logic:[Deductive Logic](https://clearthinking.substack.com/p/deductive-logic) # Deductive Logic - Notes # References / Links > [!Info]- Ignore dataview >## Backlink >Ignore this dataview. Plugins don't work on the website >```dataview Table Status, type as "Type" from [[]] and !outgoing([[]]) sort file.name asc >``` # Logic Note ## References / Links ## Publication [Deductive Logic](https://clearthinking.substack.com/p/deductive-logic) I want to give a layman's description of logical processes. Logic can prove to be a bit mindbending. I only wish to point out some principles employed in the application of sound logic. Logical arguments come in two forms: inductive and deductive. ## Inductive Logic Inductive logic can be described as working from the particular to the general. If you have an interest in birds you might wish to make a general statement about the color of "blackbirds." After viewing a million "blackbirds" you might make the inductive conclusion (generalization) that all blackbirds are black. It takes only one white blackbird to disprove the generalization. In an inductive argument, the conclusion follows only with probability from the premises. Inductive arguments have one primary distinction from deductive arguments. With the inductive argument we venture beyond the information given in the premises. ## Deductive Logic In the deductive argument, all information necessary to the conclusion exists in the premises themselves. The premises in a deductive argument can be derived either from inductive logic or pure reason i.e., a priori. Deductive arguments always follow the same pattern: **Premises + Argument = Conclusion** ### Deductive Arguments Come in Four Combinations #### First 1. If the Premises Are: True 2. And the Argument Is: Valid 3. Then the Proposition Is: Sound #### Second 1. If the Premises Are: True 2. And the Argument Is: Invalid 3. Then the Proposition Is: Unsound #### Third 1. If the Premises Are: False 2. And the Argument Is: Valid 3. Then the Proposition Is: Unsound #### Fourth 1. If the Premises Are: False 2. And the Argument Is: Invalid 3. Then the Proposition Is: Unsound Only one combination of premises and argument gives a sound logical argument. A person should always keep two important factors in mind when considering logical arguments: First, beginning with a true premise does not always lead to a sound proposition. Second, a sound conclusion does not by itself provide proof of either a true premise or a sound argument. The party making the argument can simply be lucky in arriving at a sound proposition. If you listen carefully to the conclusions that people represent as sound, many rest on either false premises or invalid arguments. Listen carefully to what people tell you about economics. Get them to give you evidence of the truth of their premises and examine carefully the validity of their argument. If they have not combined true premises with valid arguments, you have every right to doubt the soundness of their conclusion. ## Conclusion Logical arguments come in many different forms. Frequently people disguise them in regular conversation. Listen carefully to what people tell you that they hope you take as sound and don't hesitate to question the basis for the conclusion. You can find many excellent books providing an introduction to logic. I recommend that you read one of those books and engage in the hard work of speaking and writing using sound logic, and listen for the logic used by others. --- The chart used above was derived from: Albrecht, Karl, _Brain Power_. New York: Simon & Schuster, 1980, page 165 # Deductive Logic --- ## Related Topics [[Introducing the Learning Progression]] Parent::[Logic] --- # References Language & Logic:[Deductive Logic](https://clearthinking.substack.com/p/deductive-logic) # Deductive Logic - Notes # References / Links [[Searching for a Logical Man]] > [!Info]- Ignore dataview >## Backlink >Ignore this dataview. Plugins don't work on the website >```dataview Table Status, type as "Type" from [[]] and !outgoing([[]]) sort file.name asc >``` [EBook of Deductive Logic] # Logic Note ## References / Links [Inductive Logic] [Categorical Propositions] [Logic] [principle] "C:\Users\berge\OneDrive\Reference Material\Philosophy\Logic" [Logical Errors] [Logical Argument] ## Publication [Deductive Logic](https://clearthinking.substack.com/p/deductive-logic) I want to give a layman's description of logical processes. Logic can prove to be a bit mindbending. I only wish to point out some principles employed in the application of sound logic. Logical arguments come in two forms: inductive and deductive. ## Inductive Logic Inductive logic can be described as working from the particular to the general. If you have an interest in birds you might wish to make a general statement about the color of "blackbirds." After viewing a million "blackbirds" you might make the inductive conclusion (generalization) that all blackbirds are black. It takes only one white blackbird to disprove the generalization. In an inductive argument, the conclusion follows only with probability from the premises. Inductive arguments have one primary distinction from deductive arguments. With the inductive argument we venture beyond the information given in the premises. ## Deductive Logic In the deductive argument, all information necessary to the conclusion exists in the premises themselves. The premises in a deductive argument can be derived either from inductive logic or pure reason i.e., a priori. Deductive arguments always follow the same pattern: **Premises + Argument = Conclusion** ### Deductive Arguments Come in Four Combinations #### First 1. If the Premises Are: True 2. And the Argument Is: Valid 3. Then the Proposition Is: Sound #### Second 1. If the Premises Are: True 2. And the Argument Is: Invalid 3. Then the Proposition Is: Unsound #### Third 1. If the Premises Are: False 2. And the Argument Is: Valid 3. Then the Proposition Is: Unsound #### Fourth 1. If the Premises Are: False 2. And the Argument Is: Invalid 3. Then the Proposition Is: Unsound Only one combination of premises and argument gives a sound logical argument. A person should always keep two important factors in mind when considering logical arguments: First, beginning with a true premise does not always lead to a sound proposition. Second, a sound conclusion does not by itself provide proof of either a true premise or a sound argument. The party making the argument can simply be lucky in arriving at a sound proposition. If you listen carefully to the conclusions that people represent as sound, many rest on either false premises or invalid arguments. Listen carefully to what people tell you about economics. Get them to give you evidence of the truth of their premises and examine carefully the validity of their argument. If they have not combined true premises with valid arguments, you have every right to doubt the soundness of their conclusion. ## Conclusion Logical arguments come in many different forms. Frequently people disguise them in regular conversation. Listen carefully to what people tell you that they hope you take as sound and don't hesitate to question the basis for the conclusion. You can find many excellent books providing an introduction to logic. I recommend that you read one of those books and engage in the hard work of speaking and writing using sound logic, and listen for the logic used by others. --- The chart used above was derived from: Albrecht, Karl, _Brain Power_. New York: Simon & Schuster, 1980, page 165