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Epistemology: Argument and Evidence

Greg discusses the role of argument and evidence in deciding what to believe, both in philosophy and more generally.

Speaker: Dr. Greg Ganssle, Senior Fellow, Rivendell Institute, Yale University.
Created by Gaurav Vazirani.

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  • piceratops ultimate style avatar for user Christian Laube
    Isn't there a problem with the premise here, if you can prove or disprove God does depend verry much on how you define God. I know most people never bother to do so because they think it is obvious, but there are many religions and even within religions there are different definitions of God or a god. For instance if some oldfashioned Japanese told me for him the Tenno is his god. I migth disagree but it would be pretty easy for him to prove the Tenno exists. So shouldn't the first priority be establishing what you mean by God before arguing for or against his or her existence?
    (10 votes)
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    • blobby green style avatar for user Lawrence Spock
      I agree with you that it is important to define what you mean by "God". However, I don't know if Tenno-sama is a good example in this case. It is easy to prove that the Tenno exists, but the problem would be proving that Tenno is God then. Plus I would argue that no Japanese would say Tenno is God. Rather, he would say something like Tenno-sama is arabitogami or a kami-sama. Both of these words can be translated as "god", but do not mean the same thing. So since this video is in English and made by a professor at an American video, we can assume that by "god", he does not mean a being similar to the Tenno.
      (2 votes)
  • aqualine tree style avatar for user scifun
    But what if the proof needed is simply sensual: If I can see, AND touch, AND hear, AND taste, AND smell, AND know without a doubt that this is true, then it is? When you can give this proof that god is real, then most people will believe it as words mean little. So what happens then?
    (3 votes)
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    • leaf red style avatar for user Noble Mushtak
      Then you have proved God exists and debunked the claim that such can not be proved.

      To prove God exists, you could make an argument like this:
      P1: Being God is equivalent to having all of the qualities in the set C.
      P2: An object with all of the qualities in set C exists.
      C: God exists.
      This argument is valid, but you must prove P2 which is the hard part. (P1 is simply a definition of what God is, so it does not need to be proved.)

      If there is some set of true statements that logically imply P2, than you have successfully proved that God exists! On the other hand, if you have shown that there is no set of true statements that logically imply P2, than you have successfully proved that there is no way to prove that God exists!

      I'm not a philosopher, but I'm quite sure that philosophers try to make convincing cases for things instead of straight out proving things. Maybe a philosopher would present a set of premises that seem true and seem to imply P2. Perhaps then another philosopher would dig further and present sets of premises that make a convincing case for premises presented by the first philosopher, making the case for P2 even stronger! Again, I'm not a philosopher or even close to being one, and this is simply my imagination of what happens in the institution of philosophy.

      I hope this helps somehow!
      (8 votes)
  • blobby green style avatar for user Pavlos Kanellakis
    Since he focused on the importance of the premises, I'd like to examine his own opening premise "When people tell me: You can't prove God exists." Who says that? Skeptics usually ask the believers to prove their claim that God exists. Believers usually claim they can prove God exists, but that skeptics just don't want to acknowledge this. I've heard people say "You can't prove God doesn't exist" because skeptics say it as a truth claim (you can't prove a negative), and believers as an incredulity claim.

    I realize he was using the "God" argument as a delivery method for the point he was trying to make, but he started off on rather shaky ground.
    (1 vote)
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  • purple pi purple style avatar for user Yannis Kaminis
    Logic is insufficient to prove if God exists or no. We cannot explain everything with logic. But this means that God doesn't exist either. Anyway, it seems an interesting series. I am sure that this more interesting than the language series.
    (1 vote)
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  • duskpin ultimate style avatar for user tuannb1997
    I think there is a problem with your God's existence example, because whether God does exist or not, in this case, depends largely upon your personal and obviously subjective definition of EXISTENCE. Supporters of the first argument rely on nothing but their own BELIEF that God does exist, which means that, unless supernatural phenomena might be counted as PROOF of God's existence, the first argument may hardly be true. On the other hand, we can easily make use of science to point out that God does not exist: if Proof are evidence accepted widely by everyone, meaning that we must absolutely witness them with our own eyes, then God certainly DOES NOT exist, simply because NO ONE has ever seen him on Earth. So, can you clarify my confusion, please ?
    (1 vote)
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Video transcript

(intro music) Hi, my name is Greg Ganssle, and I'm a senior fellow[br]at the Rivendell Institute at Yale University. I want to start with a claim that may seem obvious to you. It is the claim that you cannot prove the existence of God. When people tell me this, I want to ask the[br]question, "How do you know? You just met me, maybe I can." The response you get, if[br]you say something like that, is that people are a little bit stunned. They take it as obvious that you cannot prove the existence of God. Now, I believe, when people say this, they are saying something true and important philosophically. But most people do not[br]know what's important about this statement. Most people think they're saying[br]something important about God. I think they're saying something[br]important about proof. What do most people mean when[br]they say a sentence like, "You cannot prove the existence of God"? Most people mean something[br]like the following: "You cannot produce reasons or evidence or an argument for the[br]claim that God exists, such that your case is so strong that it will persuade[br]everybody that God exists." Or they mean, "You cannot[br]produce the kind of evidence that will persuade a[br]very committed skeptic." Of course, all of these claims are true, but do they tell us anything about God, or whether it's reasonable[br]to believe in God? I think not. What they tell us is something[br]important about proof. Most people think about proof in terms of a kind of argument[br]that delivers certainty. We get this kind of proof when we look at disciplines like mathematics, or logic. But almost every academic discipline, philosophy, history,[br]the physical sciences, operates on a different kind of reasoning than proof that delivers certainty. This can be confusing for philosophy, because philosophers often[br]frame their arguments in what we call "deductive arguments." A valid deductive argument[br]is structured such that if the premises are true, the[br]conclusion has to be true. So, an example you'll find in many[br]textbooks is the following. Statement one: "All[br]human beings are mortal." Statement two: "Socrates[br]is a human being." Statement three: "Therefore,[br]Socrates is mortal." You can see that if statement[br]one and statement two are both true, statement[br]three has to be true. That's a good example of a[br]valid deductive argument. But in an argument like this, most of the real work is[br]done supporting the premises. So even though philosophers[br]often frame their arguments in terms of deductive proofs, most of the real work of philosophy is in supporting the premises, and this makes philosophy an[br]evidential discipline. We look for evidence. "Is the premise true? What kinds of grounds can we bring forward to support the premise?" Think about it this way. We see this kind of thing[br]on TV all of the time. Suppose a murder has been committed. What does the detective do? The detective comes in and[br]picks up little bits of stuff. And these little bits of stuff may[br]or may not become evidence. And they investigate this evidence[br]to determine who it is who is most likely to have killed the victim. They never try to get 100% certainty. They're looking to build a strong case. And if the case is strong[br]enough to convict someone beyond a reasonable doubt,[br]then they are successful. So they pick up different bits of evidence and try to fit them into[br]a story that makes sense of the claim that a particular[br]person did the crime. So there are two things we can notice about the methods of a detective. One, the case that she[br]builds is cumulative. Very rarely will there[br]be one piece of evidence that convicts the criminal. There usually are many pieces of evidence. There may be fingerprints,[br]there may be witnesses, there may be receipts, there[br]may be all kinds of things that locate the suspect where[br]the crime was committed. It's a cumulative case. Secondly, the whole approach is something that we could call a[br]"fitting-ness approach": how do we fit all these pieces of evidence together into one story? And if all the pieces of[br]evidence fit very well into one story, they support[br]the truth of the story. This is the way that philosophers work, especially if we're thinking[br]about a large claim like the claim that God exists, or the claim that God doesn't exist. These claims are overarching. It's very rarely going to[br]be one piece of evidence that strongly supports these claims. It's going to be a number[br]of pieces working together to justify, or ground, a particular[br]theory. So when we do philosophy,[br]even though we might set up our arguments[br]as deductive arguments, most of the work is done[br]in supporting the premises and bringing evidence[br]to bear on the claims we want to make. Subtitles by the Amara.org community