Tuesday, October 01, 2013

Two Kinds of Defeaters for Beliefs

The following excerpt from Philosophical Foundations for a Christian Worldview by William Lane Craig and J.P. Moreland (p.88) is a helpful explanation of defeaters for beliefs:

“One factor that affects whether and to what degree a belief is justified is the presence of defeaters for that belief. Suppose Smith has a blief that Q (e.g., that a statue is blue), and suppose that R (e.g., the way the statue looks to him) is a reason or ground Smith has for holding to Q. A defeater removes or weakens justification for a belief.

There are at least two kinds of defeaters. First, there are rebutting defeaters, which directly attack the conclusion or thing being believed. In the case above, a rebutting defeater would be a reason to believe not-Q, i.e., a reason to believe that the statue is not blue. An example would be a case where the museum director and a number of reliable, honest people assure you that the statue is grey.

Second, there are undercutting defeaters. These defeaters do not directly attack the thing believed (by trying to show that it is false), but rather they attack the notion that R is a good reason for Q. Undercutting defeaters do not attack Q directly; they attack R and in some way undercut R as a good reason for Q. In the example above, an undercutting defeater would be evidence that there is blue lighting around the statue that makes everything in that room look blue to people.

In the example, the undercutting defeater removes one’s reason for thinking that the statue is blue and the rebutting defeater gives one reason for thinking that the statue is not-blue. In different ways, defeaters can remove the justification for a belief.”


  1. Ken Pulliam July 15, 2010

    I don't see that any religious belief can be defeated by the rebuttal defeater. This is because there is no external authority that can tell us definitively if a belief is really true or false (hence my agnosticism). However, I do think that certain beliefs can be defeated by the undercutting defeater. The reason why Mormons believe their religion is because of their prior faith committment to the truth of the Book of Mormon. The reason evangelicals believe that Jesus died for their sins and rose again is because of their prior faith committment to the truth of the Bible. The same could be said of Muslims and their system of belief due to their faith committment to the Koran. IOW, the blue light of their faith makes them think the statue is blue.

    Now I can anticipate someone saying that I reject Christianity because of my prior faith committment to naturalism. However, I don't think that is the case. I reject Christianity for many of the same reasons that you reject Mormonism or Islam. The only difference is that I apply my reason consistently in rejecting all of the supernatural claims that I have examined. My reason also tells me that naturalism is a much more likely explanation for what I see.

  2. Davitor July 15, 2010

    I agree with most of Ken’s observance in naturalism except for that there being a definitive defeater for beliefs. The defeater for any beliefs are their occurrence in the life of an individual. If using the example of the statue let’s say that I live my whole life and never come across the statue or I am never told of the statue’s true color, then its true color is irrelevant.

  3. gnol6ffej July 15, 2010

    Hey Ken, that's an interesting point! When a person is trying to determine if a proposition is true they have to go back to their method of evaluating truth claims in order to see if it fits their worldview. Obviously this means that those who put their faith in the Bible must believe that it's the word of God because it say's it is.

    That leads to a sort of circular rationality, but this is the way that all beliefs work. For example when you say that you reject the supernatural because it's not reasonable to you, you're putting your reason in the same role as Christians put the Bible. If someone were to ask you why you should trust your reason you would have to say "because that's what seems most reasonable to me." Thus your forced to use you're reason to prove itself. There's nothing wrong with that, every worldview uses it's standard of truth to prove itself (that's why it's the standard) but it's unfair to say that you reject the supernatural because of this. Someone could just as easily undercut a humans ability to reason as the ultimate authority as well.

    Reason is an integral part of being human and I don't mean to vilify it. It's one of the best gifts God has given us and it's what enables us to understand Him and His creation. Not only that but it's an integral part of who God is himself. The problem is that when we base truth on our own minds were always going to run into limits. Man is personal and yet he is finite, so he is not a sufficient integration point for himself. Sartre said that "No finite point has any meaning unless it has an infinite reference point." This is true of our minds as well. This is proven when two equally intelligent people come to different conclusions based on the same information on the same topic, both using their reason as the ultimate standard of truth. If one is correct and the other not, which are morally relativistic culture may dispute haha, than it is only because the person correct is closer to using their finite mind to think the same way as the infinite mind of God does.

    Christians don't disregard reason, this site wouldn't exist if we thought there were no rational arguments for faith, but we realize that are minds are only capable of so much and would rather base our lives on divine revelation than human speculation. There are hundreds of good books to see why its reasonable to make the Bible the ultimate reference point, Josh McDowells' books are a great place to start. I'm confident that if your intent is to discover the truth and your able to push away your moral objections, you'll be led to Christ. How do I know? Because that's what my ultimate authority say's haha. I hope this helps and I'm glad you're searching, take care!

  4. Scott July 15, 2010

    Ken, your first paragraph is true enough as far you took it, however the question of beliefs and defeaters really needs to be taken a step further. Why, for example, do "evangelicals" (your term) believe that Jesus is who He said He is, or Mormons believe the Book of Mormon? It is not necessarily a blind "prior faith committment (sic)" as you state (although in a lot of religious contexts it can be).

    Such a full and comparative discussion is far too lengthy for the comments here, but I submit a good entry point for evaluating Christianity (and indeed strict naturalism) might be explaining the commonly accepted facts by scholars surrounding the resurrection of Jesus.

    For what it's worth, in my own journey from Atheism to Christianity I have not had to abstain from using any of my reasoning skills, nor has my strong sense of scepticism atrophied one iota; on the contrary, hidden biases and unjustified presuppositions were brought to the surface and examined.

    Ah, I'm already going on longer than I intended. 😛
    God bless dude, hope you give this some more thought.

  5. RkBall July 16, 2010

    "This is because there is no external authority that can tell us definitively if a belief is really true or false (hence my agnosticism)." What about God Himself? Do you think that God would not be able, through the agency of his Spirit, to convict hearts and minds?

  6. RkBall July 16, 2010

    "My reason also tells me that naturalism is a much more likely explanation for what I see."

    What you need is a reason, under the assumptions of naturalism, for trusting in your reason, why it should exist in the first place, and why human reason and logic should apparently cohere with the external supposedly undesigned, uncreated, mentally inert universe.

  7. Ken Pulliam July 16, 2010


    You said: That leads to a sort of circular rationality, but this is the way that all beliefs work. For example when you say that you reject the supernatural because it's not reasonable to you, you're putting your reason in the same role as Christians put the Bible.

    Here is the difference, reason is a human faculty and there is no way to do anything as a human without utilizing it. We all, atheists, Christians, Muslims, Mormons, etc., use our reason and trust our reason in daily activities. We have to begin with the supposition that our reason is reliable or none of us would be able to do anything. It is a totally different thing to suppose or presuppose that the Bible is a divine revelation and then base everything on that assumption. In the book, Five Views on Apologetics, edited by Steven Cowan, Paul Feinberg responds to this very issue. He writes: Here Frame commits the informal logical fallacy of false analogy. He argues that rationalists must accept reason as an ultimate starting point, just as empiricists must assume sense experience, and so on. So the Christian may begin with Scripture as a legitimate starting point. But these are not analogous bases. While the rationalist uses reason and the empiricist uses sense experience as tools from which to construct their systems, Frame assumes both the tool of special revelation and the system of Scripture, from which he develops his Christian theism. In other words, he assumes the reality of God's existence, his personal interaction with humans, plus a specific product: Scripture. Does Frame not realize that, in the name of everyone needing a presupposition, he has imported an entire worldview when the others have only asked for tools? (p. 242).

  8. Ken Pulliam July 16, 2010


    I have examined the arguments based around the so-called "minimal facts" and I find the inference that Jesus rose from the dead to be much less likely than a naturalistic explanation for the facts.

  9. Ken Pulliam July 16, 2010


    If one could know that God really was the author of the Bible and that there really was a Holy Spirit "convicting" hearts and minds, then yes, there would be an external authority telling us what color the statue is. How would one know that?

    Why wouldn't our brains cohere with our environment if we are the results of evolution? Our bodies including our brains have adapted to our environment.

  10. Scott July 16, 2010

    Ken, mind sharing what your naturalistic explanation for Jesus' resurrection is? I've come across many theories, just curious to see what version you deem more reasonable.

    Also, on reason you wrote: "Here is the difference, reason is a human faculty and there is no way to do anything as a human without utilizing it. We all, atheists, Christians, Muslims, Mormons, etc., use our reason and trust our reason in daily activities. We have to begin with the supposition that our reason is reliable or none of us would be able to do anything."

    The fact that we all use reason still doesn't address why we should trust it…or even use it when it's to our disadvantage. Atheistic evolution, an increasingly strenuous theory anyway, does not in fact assure that our senses or reasoning faculties deliver an accurate report of the external world: as Alvin Plantinga notes, mild paranoia would be a far greater aid to survival. Supposing that it's reliable (and should be employed) is a necessary leap of faith for the non-theist, one which the theist doesn't have to make as he has both an explanation for it's origin, and justification for continually utilizing it. On this point at least, you would agree that theism, if true, is a better explanation for reason/logic?

    Also, I'm not quite sure why you're comparing the Bible to our reasoning faculties; as you yourself and the passage you quote go half way to recognizing, it's a fundamental category error. As you said: "We all…Christians…use our reason". Reason is the tool by which we evaluate the Bibles claims, the Bible doesn't supplant reason, nor is the Bible just assumed to be true. Perhaps this false dichotomy has been clouding the issue for you somewhat?

    I look forward to hearing your thoughts.

  11. gnol6ffej July 16, 2010

    Hey Ken, it sounds like Paul Feinberg makes the mistake of thinking that he can accept only reason and sense data as his tools for discerning truth without having those limiting beliefs become part of his worldview. That's just not possible. It seems like he presupposes that anything beyond his own senses is off limits and than say's Christians are cheating because they go past the line he's set. But why should we live according to what he deems worthy if we believe that he has a faulty worldview to begin with? Your right, reason is a necessary human faculty for understanding, but just because something is necessary doesn't mean that it's sufficient for all understanding. If we've studied philosophy, science, history, etc. and use the reason that we do have to study the evidence objectively we certainly have enough justification to suppose that there's something beyond what Mr. Feinbergs view allows if that's where the evidence leads. Sometimes it's not a comfortable conclusion because it requires enough humility to say that we're not the judge of the universe, but it's completely valid.

    I believe that the way I became a Christian had allot to do with reason. I studied everything I could and it became evident that the arguments against Christianity were much weaker than I thought. I hated God and didn't like what I was seeing, but I couldn't use my reason as an excuse anymore. I just prayed that if God was real that he would begin to show himself to me and help me see Him for who he really is. My relationship with God has been a slow gradual process with allot of reading His word and prayer but He has become so real to me I believe in Him as much as I believe in the natural world. I can't believe the drastic change I've seen in myself the past year and a half. It's hard to explain and I'm sure you could come up with some naturalistic theories on my experience, but I believe it's legit. I could assume that God is real with my head but it wasn't until I committed to following Him that the relationship began to unfold and he became real to my whole self. It went from the objective to the subjective. Christ says, "Ask and it will be given to you; seek and you will find; knock and the door will be opened to you. For everyone who asks receives; he who seeks finds; and to him who knocks, the door will be opened." I honestly believe that if you seek truth and knock on the door of understanding you'll find Christ on the way, not in the way. Please don't take this the wrong way like I'm judging you or anything. I value your opinions. Take care!

  12. Chad July 16, 2010


    You wrote: "The reason evangelicals believe that Jesus died for their sins and rose again is because of their prior faith committment to the truth of the Bible."

    First off, if you wouldn't mind, I would like you to define what you mean by "evangelical." These days, that word is loaded and can mean many different things.

    Second, do you mean to say that ALL who believe the resurrection do so simply because of their "prior faith commitment to the truth of the Bible?"

    Thank you

  13. Ken Pulliam July 17, 2010


    An evangelical is a Protestant Christian who believes that one is saved on the basis of Christ's death and resurrection through faith alone. The term was originally applied to Luther and his followers. Today it refers to anyone who is not 1) Roman Catholic or Greek Orthodox and 2) liberal Protestant.

  14. Ken Pulliam July 17, 2010


    Feinberg is a Christian by the way. He and William Craig and Gary Habermas in the book I referenced both take issue with John Frame's presuppositonalism. They both say that reason leads them to faith whereas Frame says one must presuppose the truth of the Bible before one can make sense of it. Frame will believe what he thinks the Bible says regardless of whether it agrees with his reason.

  15. Ken Pulliam July 17, 2010

    Scott, Its difficult due to space limitations to spell out my entire theory. Simpuly put: 1) Jesus was buried in the criminal graveyard; 2) Peter had an hallucination and Paul did too later on Road to Damascus; 3) the stories of the empty tomb and the visions to groups in the Gospels are later embellishments. I have blogged about this extensively.

    If we don't assume that our senses and our reason are generally reliable then none of us would be able to function in everyday life. Thus on the basis of common sense we assume them to be reliable. One can make philosophical arguments against why it might be wrong to make such an assumption but the very philosopher making the argument assumes these same things in his daily life.

    If one uses reason to assess the Bible then I don't know how one comes to the conclusion that it is the Word of God. It seems to me that are many more reasons to believe its just the religious thoughts of ancient peoples than it is to believe it has its origin in an omniscient being. I think most Christians either a) assume its the Word of God or b) believe it is because of their religious experience (i.e., conversion). Very few if any study the Bible in detail and then come to the rational conclusion that it is the Word of God and then believe its teaching about man being a sinner and Jesus being the savior and trusting Christ for salvation.

  16. Davitor July 19, 2010

    Ken there are also other theories where Jesus survived the crucifixion due to the observance of the Sabbath and that he may have lived the rest of his live in seclusion due to the Jewish persecution and the Romans tyranny. Hence an explanation for his reappearance but oddly enough to not being recognized by his own disciples after being with him for a while.

  17. Anonymous April 8, 2012

    Hi Ken,

    It seems as though in your denial of the resurrection you are actually going back on your positions that human reason is trustworthy. If the historical accounts of the resurrection are due to hallacination, what is to say that any experience of ours is not the result of hallucination?

    This to me is one of the real problems with explaining historical accounts by hallucination. To do so you have to say that actually our sense perception and reason do not connect with reality during the hallucination event. So it comes across as special pleading to say that our reason is reliable in all circumstances, except those that disagree with your worldview.

  18. Brian Auten April 8, 2012

    Note than Ken died last year, I am sad to say.

  19. Paul Taylor October 2, 2013

    So now Ken knows that he was wrong. 😐

    I belive RkBall hit the nail on the head. God is capable of providing the external authority necessary in a situation like this, and is able to do so independently of whether we are able (or whether we consider it reasonable) to believe in the evidence or claims he makes.

    I could believe in Jesus based on what the Bible says, assuming I believe what the Bible says first. But God is certainly capable of bringing me to a position of absolute certainty by his own direct operation in my life. Once he has done so, my belief in the Bible can follow that, rather than precede it. If does not do so, I may remain for ever among those who believe what the Bible says but have no saving knowledge of God.