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Fundamentals: Introduction to Critical Thinking

Geoff Pynn gets you started on the critical thinking journey. He tells you what critical thinking is, what an argument is, and what the difference between a deductive and an ampliative argument is. 

Speaker: Dr. Geoff Pynn, Assistant Professor, Northern Illinois University.
Created by Gaurav Vazirani.

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  • leaf yellow style avatar for user turtleshell
    What if the arguments don't lead to a strong probability, but are still logical arguments. For example: "I don't think Monty will be at the party because he might have to study for his philosophy class." In this case, I am not sure if Monty has to study or not. His attendance is probably less likely than than if he didn't have any coursework, but that is all I can be sure of.

    How probable does the conclusion need to be to be considered a good ampliative argument?
    (35 votes)
    Default Khan Academy avatar avatar for user
    • leaf green style avatar for user Stuart W
      If the "logical" arguments do not tend to lead to the fulfillment of the conclusion, then the premises could be contradictory, or the arguments may lack an implicit premise. This could mean they are not actually logical, but I will get to this. Allow me to reform your argument a bit so we may comfortably bite into it.

      P1. Monty is enrolled in a philosophy course.
      P2. Monty needs to spend time studying.
      C. Monty won't be at the party.

      By itself this is not very consistent. It assumes he will spend the time of the party at home studying. Whoever posits this statement should perhaps use another premise or two such as: "Monty hasn't been keeping up with course-work"; "there is a philosophy midterm tomorrow". These make the conclusion more logical to someone reading premises and conclusions on paper, but may, of course, be common knowledge to a member of the conversation.

      In the equivocal form you first presented this "logic", you ask to know how probable this must be in order to be considered a good ampliative argument. This, conversationally, depends on who is listening and if they agree with you. Yet, formally, these instincts are unfortunately a large part of critical thinking and philosophy (I'm especially thinking of Bentham's felicific calculus, or "moral calculator"). While there are empirical methods for declaring an argument flawed, especially with logic, the people evaluating the argument will naturally project their persuasion on the evaluation. In practice, the conclusion needs to be probable enough for both the speaker and the evaluator(listener) to believe.

      tl;dr It depends
      (31 votes)
  • ohnoes default style avatar for user Cyan Wind
    I have watched all the vids in this subject. They are very interesting. However, I have a question: The illustrator frequently draw a cat wearing glasses in these vids. What does that cat stand for?
    (26 votes)
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  • ohnoes default style avatar for user Cyan Wind
    How should I call theories/models in science: ampliative or deductive? Scientists can use a lot of evidences to prove their theories/models, however, there is always a chance that it can be wrong because of unforseen factors.

    Oh wait, can I apply philosophy into science?
    (8 votes)
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    • old spice man green style avatar for user Jessica Gallegos
      I think that we can and do there are some theories which have more concrete premises that hold more weight say evolution they have a lot of evidence such as fossil record that would have a causation to be deductive. And other theories such as parallel universe which as far as I know does not have as much evidence to support the theory. So Deductive arguments are in use in good science.
      (7 votes)
  • male robot hal style avatar for user Wudaifu
    Premise 1: In the video, the speaker spelled "guarantees" @ and "guaranteed" @ .
    Premise2: In the conclusion of the video, the speaker spelled "gaurantee" @ .
    Conclusion: These premises may shed some doubt on the accuracy of other parts of the video.

    Is what is written above a correct example of an "ampliative argument"?
    (6 votes)
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  • purple pi pink style avatar for user PERCE-NEIGE
    I've got some exercices for you, to help us undertand and dig the ideas out :-)
    (you can reply to only one question or several ones)

    1/ What is the difference between logics and critical thinking?
    2/ When do we need our critical thinking?
    3/ Can you give example of a lack of critical thinking you met in your life?
    4/ Can you give a short definition in a sentence of "critical thinking"? What is the opposite of critical
    thinking?
    5/ Can you give the bad reasons and the good reasons for believing something (in general, not as an example)
    (5 votes)
    Default Khan Academy avatar avatar for user
    • leaf green style avatar for user Agent Smith
      1. Logic is the study of arguments. Critical thinking is application of logic.

      2. Without critical thinking we would not survive for long. Even if we do, life would be empty

      3. TV ads and newspapers are full of it

      4. Critical thinking is clear and logical thinking.

      5. If a thing is supported by sound/cogent arguments, we should believe it. Emotional basis for believing something is always bad.
      (4 votes)
  • aqualine ultimate style avatar for user Estera Anastasiu
    We want to be rational, we aim toward being rational, but most times we fail to be so. One cannot question everything in order to believe it, in order to act in accordance with it. Most mundane eg. How can you be sure about the food you are about to eat? You start with the premise that it is not poisoned, that it is what you think it is, that it is you who are about to eat it, etc. Kind of like Matrix.
    So, my question would be, when making all this statements about humans being rational, what are your premises?
    (3 votes)
    Default Khan Academy avatar avatar for user
  • leaf green style avatar for user Agent Smith
    Since we are required, by logic, to provide a logical foundation/basis for every belief, I want to know what is the basis of logic itself. What is the evidence that proves/shows that we should be logical?
    (2 votes)
    Default Khan Academy avatar avatar for user
    • blobby green style avatar for user Geoff Pynn
      That's a good question. Here's the start of an answer: by employing logic and good reasoning, we help to ensure that we form true beliefs and don't form false beliefs. And true beliefs are preferable to false beliefs. For example, suppose that you are hungry and find a loaf of bread. The loaf of bread is poisoned. Is it better for you to have the true belief that the loaf is poisoned or the false belief that the loaf is safe?
      (3 votes)
  • male robot hal style avatar for user Corey Piper
    What if you make a deductive argument for an ampliative conclusion:
    P1: The sun has risen everyday since formation of earth
    C: It is likely the sun will rise tomorrow.
    I don't know if it's possible to have a non-guarenteed conclusion like that, but if the premise is true, it surely does make the sun giving rise tommorow very likely. All though it may not be true, is this still a deductive argument in the sense the premise does guarantee, not the sun rising, but rather just the likelihood of it?
    I guess more or less my question is can you guarantee a probability?
    (2 votes)
    Default Khan Academy avatar avatar for user
    • leaf green style avatar for user Agent Smith
      Here's what I think about your interesting question.

      You mean to say that we're sure/certain that inductive arguments are probable. Thus, giving a deductive character to inductive arguments. Well, you're right. Here are two arguments here: 1) the inductive argument itself and 2) your argument about inductive arguments.

      1) inductive arguments are about probable conclusions
      2) Your argument about inductive arguments is deductive.

      I think we should not confuse the two.
      (3 votes)
  • piceratops ultimate style avatar for user Tiger
    In Lincoln-Douglas debate, we use contentions to support our conclusions. Are premises the same as contentions?
    (2 votes)
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  • leaf green style avatar for user josselinchavez7
    Can an ampliative argument be the same as a hypothesis or an infrence?
    Does a deductive argument ever go wrong or give a false conclusion?
    Is an ampliative argument sometimes right and useful for serious matters?
    (2 votes)
    Default Khan Academy avatar avatar for user
    • leaf green style avatar for user Agent Smith
      A hypothesis is usually an "explanatory" proposal e.g. you see objects falling to the ground and you hypothesize a force that causes this phenomenon. You need arguments to prove this hypothesis and usually the arguments are ampliative.
      An inference is the process of affirming the conclusion from the premises.
      Yes, a deductive argument can lead to false conclusion if it either contains a fallacy or if the premises are false or both.
      All of science is based on ampliative arguments. Yes, ampliative arguments are useful
      (1 vote)

Video transcript

(intro music) I'm Geoff Pynn. I teach at Northern Illinois University, and this is an introduction[br]to critical thinking. In this lesson, we're gonna[br]talk about three things. First, what is critical thinking? Second, what is an argument? And third, what's the difference between deductive and ampliative arguments? Okay, so what is critical thinking? Well, fundamentally, critical thinking is about making sure that you have good reasons for your beliefs. What does that mean? So suppose that you and your friend are talking about who's[br]gonna be at tonight's party. And she says to you, quite confidently, "Monty won't be at the party." You're not sure whether[br]or not to believe her, so it would be natural[br]for you to follow up by asking, "Why do you think so?" And there are a lot of different things that she might say in response. We're gonna talk about three possible answers she could give. First, she might say, "I can't stand him, and I want to have a good time." Second, she might say,[br]"Well, he's really shy, and he rarely goes to parties." And third, she might say, "He's in Beijing, and it's impossible to get here from[br]Beijing in an afternoon." The first response that she gives you does not give you a good reason to believe that Monty won't be at the party. The second reason,[br]though, is a good reason to believe that Monty[br]won't be at the party. If he's really shy and[br]rarely goes to parties, then it's probable that he[br]won't be at tonight's party. Similarly, the third reason[br]also gives you a good reason to believe that[br]Monty won't be at the party. If he's in Beijing, and[br]it's impossible to get here from Beijing in an afternoon,[br]then it's guaranteed that he won't be at the party. And when you notice things like that, when you distinguish between good and bad reasons for believing something, you're exercising your[br]critical thinking skills. So critical thinking is making sure we have good reasons for our beliefs, and so one of the essential[br]skills that you learn when you're studying[br]critical thinking is how to distinguish good reasons[br]for believing something from bad reasons for believing something. Now, it's worth saying something about how I'm using the term "good" here. I'm not using it to indicate anything having to do with morality or ethics. So it's not morally right or morally good to believe something on[br]the basis of good reasons. Similarly, it's not morally[br]wrong, or evil, or wicked to believe something on[br]the basis of a bad reason. Rather, here, what it is to[br]say that a reason is good is closely tied to the notion of truth. So a good reason for a belief is one that makes it probable, that is, it's one that makes the belief likely to be true. The very best reasons for a belief make it certain, they guarantee it. So why does this matter? Well, the reason that critical thinking is important is because,[br]since we're rational, we want our beliefs to be true. Rational people want to have true beliefs, and they want not to have false beliefs. And the best way to be[br]rational in this way is to form beliefs only when you find good reasons for them. Okay, that leads us to[br]our second question: What is an argument? Well, an argument is a set[br]of statements that together comprise a reason for a further statement. So, for example, we can consider one of your friend's responses[br]before as an argument. She's given you two statements, "Monty's really shy" and[br]"Monty rarely goes to parties," which together comprise[br]a reason for believing that Monty won't be at the party. The statements that are the reason, we call the argument's premises. So "Monty's really shy" is premise one, "Monty rarely goes to[br]parties" is premise two, and the statement that[br]those premises give you reason to believe, we call[br]the argument's conclusion. A good argument is one[br]in which the premises give you a good reason for[br]the conclusion, that is, the premises make the[br]conclusion likely to be true. In that case, we say that the argument supports the conclusion. Good arguments support their conclusions, and bad arguments don't[br]support their conclusions. So a key part of critical[br]thinking is learning to evaluate arguments to determine whether or not they're good or bad, that is, whether or not their premises support their conclusions. The red argument is the first response that she gave, two premises, "I can't stand Monty" and "I[br]want to have a good time." And the conclusion is "Monty[br]won't be at the party." And the third argument,[br]which we'll put in purple, consisted also of two premises, "Monty's in Beijing" and[br]"He can't get from Beijing to the party in time, so[br]he won't be at the party." Now, as I indicated[br]before, the first argument is not good, while the[br]purple argument is good. And here I can explain a[br]little bit more about why. If you consider what the[br]red argument's premises say, that your friend can't stand Monty, and she wants to have a good time, and think about their relationship to the conclusion of the argument, you'll see that those[br]statements don't make that conclusion any[br]more likely to be true. The fact that your[br]friend can't stand Monty and wants to have a good[br]time doesn't do anything to make it more likely[br]that Monty won't be there. It's simply unrelated to the conclusion. In the purple argument,[br]though, the premises, if they're true, they guarantee[br]the conclusion is true. So they make it very probable. The truth of the premises[br]guarantees the truth of the conclusion, and so[br]in the purple argument, the premises do support the conclusion. Now, it's worth pointing[br]out that the red argument, though it's bad as it[br]stands, could be made a good argument with the addition of some background premise. So, for example, if you found out that your friend was[br]the person who decided who was going to be invited to the party, then the fact that she can't stand Monty and wants to have a good time would give you a good reason to believe that Monty won't be at the party, because it would give you reason to believe that she didn't invite him. But as it stands, the[br]argument is not good. Those two premises[br]considered in themselves give you no reason to believe that Monty won't be at the party. Okay, our last topic is to distinguish two different types of arguments. So I'm gonna put up here, on the left, the orange argument, which is the second response that your friend gave, "Monty's really shy" and[br]"He rarely goes to parties." On the right we'll put[br]the purple argument, "Monty's in Beijing" and "He can't get from Beijing[br]to the party in time." Both of them have the same conclusion, "Monty won't be at the party." Now, as I said before, both of these are good arguments, they both do give you reason to believe the conclusion, i.e., both of them have premises which support the conclusion, but there's an important difference between the two arguments[br]that I want to point out. If you consider the purple argument, and think about what those premises say, you'll notice that if[br]those premises are true, if Monty's in Beijing,[br]and can't get from Beijing to the party in time, then it must be true that Monty won't be at the party. Those premises guarantee the conclusion. In such an argument, where the premises guarantee the truth of the conclusion, we call the argument deductive. In a deductive argument,[br]given the premises, the conclusion must be true. Just thinking about the information in the premises in a deductive argument gives you all you need[br]to deduce the conclusion. If you look at the[br]orange argument, though, you'll notice that that's not the case. In the orange argument,[br]even if those premises are true, the conclusion[br]might still be false. Even given that Monty is really shy and rarely goes to parties,[br]it's still possible that he'll get over[br]his shyness and suspend his policy of rarely going to parties, and unexpectedly show up. It's unlikely, but it's possible. So the truth of the premises[br]in the orange argument does not guarantee the[br]truth of the conclusion. Arguments like this, we call ampliative. In an ampliative argument,[br]the truth of the premises makes the conclusion probable[br]but doesn't guarantee it. Now, as I said, both of[br]the arguments are good. Ampliative arguments can often be very good arguments,[br]they're just not deductive. The premises don't guarantee[br]the truth of the conclusion. Now, when you're evaluating an argument, it can be important to know whether or not the argument is supposed to be deductive or supposed to be merely ampliative. If an argument is[br]supposed to be deductive, but careful consideration of the argument reveals that in fact the premises don't guarantee the[br]truth of the conclusion, if the conclusion could[br]be false even though the premises are true,[br]that's often a good reason to reject the argument as a bad argument. Whereas in an ampliative argument, to notice that the truth of the premises doesn't guarantee the[br]truth of the conclusion, is simply to notice that[br]it's an ampliative argument. If you were to object[br]to the orange argument by pointing out that,[br]still, the conclusion could be false, you'd[br]really be missing the point. In an ampliative argument,[br]it's taken for granted that the conclusion is not[br]guaranteed by the premises. Rather, what an ampliative[br]argument is doing is giving you reasons to think that the conclusion is probable. So knowing what type of[br]argument an argument is is essential to knowing which tools to use to evaluate whether or[br]not it's a good argument. And we'll talk quite a bit more about different tools for[br]evaluating both ampliative and deductive arguments in future lessons. Okay, so summing up this lesson. Critical thinking is making sure that we have good reasons for our beliefs, where we understand a good reason as one that makes the belief[br]probable, or likely to be true. An argument is a set of statements, which we call premises,[br]that together comprise a reason for another statement, which we call the argument's conclusion. And in a good argument, the premises support their conclusions, that is, the premises give you a[br]good reason for believing the conclusion, because[br]they make it probable. A deductive argument is[br]one where the conclusion is guaranteed by the premises.[br]If the premises are true, then the conclusion must be true. An ampliative argument[br]is one where the premises don't guarantee the conclusion, but they do make it probable. So they can still provide you with good reason for[br]believing the conclusion. Okay, so that ends this[br]introductory lesson. Subtitles by the Amara.org community