Deductive reasoning - Intro to Psychology
Summary
TLDRThe video explores deductive reasoning through examples. The first example demonstrates valid deductive logic, concluding that all objects create gravity based on true premises. It highlights that correct conclusions follow when the premises are true. However, a second example about math shows how false premises can lead to incorrect conclusions, even with a logical structure. This showcases how deductive reasoning can only lead to accurate results when the premises are valid. The video then transitions to Susan for a discussion on inductive reasoning.
Takeaways
- 🔍 Deductive reasoning starts with general premises and moves to a specific conclusion.
- 🌀 Premise A: All mass creates gravity.
- 🔗 Premise B: All objects have mass, leading to the conclusion that all objects create gravity.
- ✔️ Deductive reasoning leads to a true conclusion if both premises are true.
- ⚠️ However, deductive reasoning can only lead to accurate conclusions if the premises themselves are true.
- 📉 Example: Premise A (I don't know math) and Premise B (I can't learn math) lead to a false conclusion (I shouldn't try to learn math) because both premises are false.
- ⚖️ Even though both arguments follow a similar structure, one leads to a true conclusion, while the other does not.
- 🧪 Scientists often use deductive reasoning to make predictions based on general goals.
- 🧐 Deductive reasoning is effective for structuring logical arguments when the premises are correct.
- ➡️ The next discussion transitions to Susan, who will explain inductive reasoning.
Q & A
What is an example of deductive reasoning mentioned in the script?
-The example given is: Premise A: All mass creates gravity, and Premise B: All objects have mass. Therefore, the conclusion is that all objects create gravity.
Why does the logical conclusion in deductive reasoning have to be true?
-The logical conclusion has to be true if the two premises are true because deductive reasoning ensures that the conclusion follows logically from the premises.
What is the flaw in the second example of deductive reasoning?
-In the second example, Premise A (I don’t know math) and Premise B (I can’t learn math) are both false, which leads to a false conclusion (I shouldn’t try to learn math).
Why is the conclusion in the second example of deductive reasoning false?
-The conclusion is false because both premises are false, showing that the reasoning is flawed even though the structure is deductively valid.
What distinguishes accurate conclusions from inaccurate ones in deductive reasoning?
-Accurate conclusions come from true premises, while inaccurate conclusions arise when the premises are false, even if the reasoning structure is valid.
What type of reasoning do scientists use when making predictions for general goals?
-Scientists use deductive reasoning when making predictions for general goals.
Can deductive reasoning always lead to correct conclusions?
-Deductive reasoning can only lead to correct conclusions if the premises it is based on are true.
What role do the premises play in deductive reasoning?
-The premises provide the foundational statements from which the conclusion is drawn. If the premises are true, the conclusion must also be true.
How does the structure of deductive reasoning remain the same in both examples?
-Both examples use the same logical structure of premises leading to a conclusion, but the truthfulness of the premises determines the accuracy of the conclusion.
What is the transition made at the end of the script?
-The transition is from discussing deductive reasoning to introducing inductive reasoning, with Susan being mentioned to explain inductive reasoning.
Outlines
🧠 Understanding Deductive Reasoning
The paragraph introduces deductive reasoning by explaining its structure and logical flow. It presents Premise A: 'all mass creates gravity' and Premise B: 'all objects have mass.' From these premises, the conclusion 'all objects create gravity' follows logically. The paragraph emphasizes that for deductive reasoning to lead to correct conclusions, the premises must be true. The example provided shows a valid logical conclusion based on true premises.
🤔 Flawed Deductive Reasoning Example
This part demonstrates how deductive reasoning can lead to a false conclusion if the premises are incorrect. Using the example, Premise A: 'I don’t know math' and Premise B: 'I can’t learn math,' the false conclusion is 'I shouldn’t bother trying to learn math.' The paragraph highlights that despite the reasoning being logically structured, the argument fails because both premises are false. This demonstrates the importance of valid premises in deductive reasoning.
🔬 Deductive Reasoning in Science
The paragraph briefly transitions to how deductive reasoning is applied in scientific contexts. Scientists use this method to make predictions based on general principles or goals. The text serves as an introduction to the next segment, which will discuss inductive reasoning, teasing a shift in focus to Susan's perspective.
Mindmap
Keywords
💡Deductive Reasoning
💡Premise
💡Gravity
💡False Premise
💡Conclusion
💡Inductive Reasoning
💡Scientists
💡Logical Structure
💡Accurate Conclusion
💡False Conclusion
Highlights
Premise A: All mass creates gravity.
Premise B: All objects have mass.
Conclusion: All objects create gravity.
Deductive reasoning: If premises are true, the conclusion must be true.
Deductive reasoning can lead to correct conclusions if general premises are true.
Example of false premises: Premise A - I don't know math.
Example of false premises: Premise B - I can't learn math.
False conclusion: Therefore, I shouldn't even try to learn math.
False premises lead to inaccurate conclusions.
Deductive reasoning: Same structure can lead to true or false conclusions depending on the truth of the premises.
Accurate deductive reasoning relies on valid premises.
Scientists use deductive reasoning to make predictions for general goals.
Deductive reasoning is critical for scientific predictions.
The example of reasoning about math demonstrates the importance of premise accuracy.
Transition to Susan for inductive reasoning discussion.
Transcripts
So let's look at an example of deductive reasoning. So Premise A, is all mass
creates gravity. And Premise B, is all objects have mass. Therefore, all
objects create gravity. Because if all mass has gravity and all objects have
mass, then they must create gravity. Notice that the logical conclusion has to
be true if the 2 premises are true. We know, however, that this type of
reasoning can lead to correct conclusions only when the general premises to
which they are based are true. Let's look at another example. Premise A,is I
don't know math. Premise B is, I can't learn math. Therefore, I shouldn't even
bother trying to learn math". We see, here, that this reasoning leads to a
false conclusion, because premise A is false. And so is premise B. So, even
though the argument is. Easily structured in the same way. One leads to an
accurate conclusion, and one, this one, does not. Deductive reasoning is what
scientists use when we make predictions for our general goals. Now let's go to
Susan and talk about inductive reasoning.
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