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    Knowledge & Proof Do Not Require Certainty

    Written by Michael Horner

    There is a great deal of confusion over two words know and prove. Not everyone uses these words in the same way. I think this was part of what was contributing to some further confusion during the recent debate at the atheist’s convention over two other words, probability and certainty. This confusion over the issue of probability was the most surprising thing about the debate for me. Both DiCarlo and Dillahunty seemed to have no idea of what I even meant when I said that our arguments for God were probabilistic in nature!

    Knowledge is warranted true belief. In other words, knowledge is a true belief that you have good reasons for holding. Knowledge does not require certainty. If knowledge is limited to only that which it is logically impossible to be mistaken about, we would hardly know anything at all. And as much as atheists like to claim they are skeptics, there is hardly anyone in the world who really is a knowledge skeptic to that degree. We all think that we know lots of things, and rightly so.

    Philosopher Alvin Plantinga has shown that even though it is possible that we are all brains in a vat (imagine the Matrix), we are still rational to claim that we know that the world exists, and what I am experiencing is not an illusion, that this truly is my body moving about this world and those truly are other bodies that are doing the same.

    Moreover, even though there is no way to prove with certainty that there are other minds other than just our own, we are rational to claim to know other minds exist. Even though it is possible that the world was created five minutes ago with appearance of age, and each of us with built-in false memories, it is still rational for us to claim to know that the world, including ourselves, have truly existed longer than five minutes.

    These are all examples of knowledge that we have even though it is logically possible that we are mistaken.

    Furthermore, this type of skepticism is self-defeating. If one asks the skeptic his justification for thinking knowledge requires certainty, what would he say? Any response can be replied with the question, “Are you certain of that?” If he says “No,” then, on his own view, he doesn’t actually know that knowledge requires certainty. If he says “Yes,” then it‘s not true that we can’t know anything apart from certainty.1

    There is also confusion over the words prove or proof. When I use these words I do not mean showing something to be true with absolute certainty, or as our atheist opponents put it, absolutely without doubt. I mean that I can provide good arguments and evidence for the truth of a proposition.

    All three of the arguments for God’s existence we presented at the conference were introduced in the form known as ‘inference to the best explanation.’ God is the best explanation for the beginning of the universe; for the fine tuning of the universe for intelligent life; and for the existence of objective moral values & obligations.

    There are other possible explanations for this data. But God, we argued, is the best explanation for each of them, better than the universe popping into existence uncaused out of absolutely nothing; better than chance explaining the extraordinary improbabilities of the fine tuning; & better than any naturalistic attempt to explain objective moral values & obligations.

    It is in this sense that I claimed the theistic arguments are probabilistic in nature. Even though there are other logically possible explanations, God is the most probable explanation. The existence of other possible explanations is not enough to defeat the arguments. Possibilities come cheap! These other possible explanations must be shown to be more probable than the God hypothesis.

    In my next post I will discuss the deductive form of our three arguments for God and the difference between the truth value of a premise and our confidence in the truth of the premise.

    Question: Do you think that you know some things even though they cannot be proved with absolute certainty?

    1. Does Knowledge Require Certainty? Q & A #187, Reasonable Faith Website, http://www.reasonablefaith.org/does-knowledge-require-certainty


    One Response to “Knowledge & Proof Do Not Require Certainty”

    • Antony Burt says:

      Hi Michael,

      I did not think we would be touching on solipsism (the view or theory that the self is all that can be known to exist), but ok, let’s delve into it a little further and see where it takes us:

      I don’t agree with solipsism as a stance on reality, but for this post, I will swap sides and argue for it…

      Why is there such a train of thought as solipsism in philosophy? Basically because we have no way of knowing absolutely anything, other than our own thoughts. Our full range of senses are filtered through our brains (if we indeed have one) and we have no direct access to the actual reality we live in. All of our sense of reality is dependant on our brains, which is dependant on our senses. We do live in Plato’s cave (watching reflections of reality and never reality itself.) Our perception of reality is only a perception, and nothing more. If our senses were manufactured for us, or otherwise false, we truly could not recognize it. This is the arena of ‘brain in a vat’ or ‘5 minute universe’ scenarios.

      While the ‘brain in a vat’ or ‘5 minute universe’ concepts are interesting, do we give them much credit beyond discussion over beer and pizza? Not much, but why? Why do we not fully entertain the thought that we are indeed alone in a computer simulation, our world is younger than we appear, or that our entire reality is ensconced within a miniature town with trains that only come back (a la the Twilight Zone episode: Stopover in a Quiet Town.) We are naturally skeptical of these scenarios as they carry a huge degree of implausibility that makes them naturally unlikely. A fully developed scenario where all of our sensuous input must be provided for us would require an inordinate amount of detail. This is shown in the Stopover in a Quiet Town episode of Twilight Zone, when the subjects found their world to be lacking in even mundane details they normally expected. The squirrels didn’t move (they were mere stuffed), the cupboards were filled with props, etc. The required amount of detail to develop the scenario to be deployed without a chance of detection of the false reality would need to be mapped to at least the molecular level and would require no less than a deity of some sort just to accomplish the depth of detail required (either a creator of the universe, or one of the trickster deities (like Coyote or Loki)).

      Michael discusses the Five Minute Universe scenario (wherein we inhabit a universe which is but a scant 5 minutes of age, but the universe seems much older and our memories span back more than 5 minutes due to what would seem to be supernatural intervention). Michael says it is rational to dismiss the scenario and accept the universe instead as it seems. Interestingly in contrast to an earlier blog post that Michael co-authored with Paul Chamberlain (“Guest Blog by Dr. Paul Chamberlain: “Do All Truth Claims Come With A Burden Of Proof?”) does not feel the need at this point to provide proof to back up his negative claim, relying instead on ‘rationality’, but should we? Can we dismiss this scenario with a simple wave of the hand, or do we need to stake our negative claim to proofs to be valid?

      Before we look at dismissing the Five Minute Universe, we should clarify it a little better:

      Even though the universe is ‘truly’ Five Minutes old, all of our fields of science seem to agree that the world is approximately 4.5 billions years of age, and that the universe is approximately 13 billion years old. Light from other galaxies seems to have taken billions of years to get to us. All valid science points to a universe that has started some 13 billion years prior to the ‘true’ beginning of the universe.

      As I mentioned previously, to create a universe plus create the sciences of discovery that can not accurately divulge the true age of the universe would require one or more deities to master mind and build the scenario. Therefore the 5 Minute Universe could only suitably exist with the aid of a god which we will call Five Minute Universe God (or FMUG for short. I have it on good authority He does not mind an Acronym moniker):

      Validation for the Five Minute Universe God (FMUG)

      Validation argument #1
      1) Whatever begins to exist, has a cause.
      2) The universe began to exist 5 minutes ago.
      3) Therefore, the universe has a cause.
      4) That cause could only exist prior of the creation of the universe, so it would needfully be a timeless, causeless, spaceless, personal being of immense immeasurable power. That cause could only be the creator of all: the FMUG.

      Validation argument # 2
      1) A miracle is any event whose only adequate explanation is the supernatural intervention of a god.
      2) People having memories past their creation 5 minutes ago would indeed be a miracle.
      3) Therefore the creator of all: the FMUG, exists.

      Validation argument #3
      1) Belief in at least one god, is common to many cultures of almost any era of recorded human civilization on earth.
      2) Either the vast majority of people have been wrong about this most profound element of their lives or they have not.
      3) It is most plausible to believe that they have not.
      4) Therefore it is most plausible to believe that a god exists.
      5) Therefore it is most plausible that the god is the creator of all: the FMUG.

      These simple arguments while not fully concrete, are highly probable in the conclusions they reach. They show that logically, the FMUG exists. And if FMUG logically exists, it stands to reason that logically FMUG exists in reality. While other possible scenarios may exist, say that the universe is a little bit older, say six or ten thousand years old, that FMUG does NOT exist, or that FMUG created the universe 13 million years ago, but let science show the correct age of the universe does it mean they do exit as in a multiverse, or replace our scenario as the only scenario option. As Michael Horner says “The existence of other possible explanations is not enough to defeat the arguments. Possibilities come cheap. These other possible explanations must be shown to be more probable…”

      We can we not just dismiss the FMUG and It’s universe with a wave of the hand and a quip that the five minute universe is irrational? Are the three arguments for FMUG themselves irrational? Is the schema of a God creating a universe irrational? Is it irrational to propose that a God would create a universe, then create fields of science to hide the true origins of the universe? If these are irrational, or rational what does that mean for other similar or dissimilar scenarios?

      Which other scenarios are more probable and why are they more probable? Is it more probable to just simplify the scenario (for example a scenario which does not require the miracle of memory alteration is possibly more probable)? If we can create a more probable scenario by simple reduction of complexity, at what point should we stop? The most simple explanation is that we are simply the product of a god, with no universe or science, not even any brains in a vat, but a product of a thought experiment by a deity (like a computer simulation program, only devised and run fully within the a deities mind.)

      Is the simplest scenario the best scenario? Is the most complex scenario better? How do we know the best scenario for our ‘reality’? We have no way of knowing for certain (as we have no direct link to reality), but we can likely find a most probable scenario at least for ourselves to believe in. What makes your version of reality most probable for you may be different for other peoples. I suppose it depends on what you classify as most probable or not…

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