Skepticism v Falliblism

Ben Stear

Theory of Knowledge


PART 1: Global Skepticism argues that it is not possible to be absolutely certain of anything. In other words, according to the global skeptic, it is impossible for anyone to know anything. Because global skepticism denies that we are able to have knowledge of anything, it is also known as universal skepticism. On the other hand, a limited skeptic is someone who is skeptical about one or more specific classes of knowledge. A limited skeptic does not deny that we are able to know things, but he or she will argue that there are certain areas of knowledge that we do not or cannot know. For example, a future skeptic denies that it is possible to know anything about the future. Similarly, a Mars skeptic believes that any knowledge of the planet Mars is not knowable. External world skepticism is somewhere in the middle, but is considered a type of limited skepticism. The external world skeptic believes that we do not know anything about the external world. Usually, ‘external world’ refers to any proposition describing the world around us. Anything besides our own inner consciousness is considered to be part of the external world. If someone is an external world skeptic they not only believe that knowledge of the external world is unobtainable, but that it also may not even exist.

Part 2: Two arguments that Feldman makes for external world skepticism are “the possibility of error argument” and “the certainty argument”. The possibility of error argument states that for (almost) any belief any person has about the external world, that belief could be mistaken. And if the belief could be mistaken, then it is not a case of knowledge. Therefore, almost any belief a person has about the external world is not a case of knowledge. I view the possibility of errors argument as the classic skeptical argument (not so much for external world skepticism as Feldman postulates, but limited skepticism in general.) It forces us to reexamine our level of knowledge about the external world. In Meditations, Decartes writes, “…on many occasions I have in sleep been deceived by similar illusions, and in dwelling carefully on this reflection I see so manifestly that there are no certain indications by which we may clearly distinguish wakefulness from sleep…”. Here, Decartes is providing an example of the possibility of error argument by admitting he may be mistaken in believing he is awake when in reality he is asleep. He reasons that when he is having a dream he does not know that he is having a dream and therefore he could be fooled by his own mind as to whether he is awake or asleep. Famously, Decartes claims cogito ergo sum, which means I think, therefore I am. The possibility of error argument includes the ‘almost’ in it’s definition because of this belief. Decartes reasons that even if the external world is all an illusion he cannot be wrong about existing because he has the ability to think and question his reality. The possibility of error argument is also compatible with the argument that it is not impossible for you to be a brain in a vat that reproduces all of your perception and experiences of everyday life flawlessly. If you cannot disprove this claim then it seems that the skeptic isn’t unjust in saying that you don’t know your not a brain in a vat. Importantly, the skeptic is not at all claiming that you are a brain in a vat, but that you do not know if you are or are not a brain in a vat. This skeptical argument tries to tell us that there is always room for error in our knowledge.

Another argument Feldman makes for external world skepticism is “the certainty argument”. This argument is related to the possibility of error argument in that it has to do with fallibility. The certainty argument says that if you know a proposition then you are absolutely certain of the proposition. Because you cannot be absolutely certain about anything (in the external world) then you have no (external world) knowledge. It is important to understand the meaning of certainty in the philosophical context. Psychological certainty has to do with how strongly one feels about their knowledge of something. Epistemic certainty, which is what this argument has to do with, deals with having the strongest possible reasons for knowing something. This argument claims that no one can have infinitely strong reasons for knowing something and thus they do not have epistemic certainty which means they do not know anything (about the external world). The debate here seems to be whether absolute epistemic certainty is required to truly know something. How much evidence or reasoning is required to know something and what exactly do we mean when we say we know something? These two questions are answered unapologetically by the skeptic, who then concludes we have no epistemic certainty about the external world, therefore making it possible that it does not exist at all.

Part 3: Feldman answers the skeptics with falliblism. The main premise of falliblism says that the skeptic “presupposes an unreasonably high standards for knowledge” (Feldman, 122). Basically, the skeptic’s arguments are based on the belief that knowledge requires absolute certainty, which is a very high standard indeed. So high in fact that it leads us to the obvious conclusion, that we are incapable of knowing anything. Most people believe that knowledge requires very strong reasons but absolute certainty is not necessary (or possible). Even the scientific community, who require very, very strong evidence to support a claim, do not rely on absolute certainty for knowledge. A fallibiist will say that when you see a table in front of you it is reasonable to say “I know there is a table in front of me”. The fallibilist believes that you are justified in believing that you know there is a table in front of you due to your evidence through sensory perception. While the possibility exists that you may be wrong or are being deceived, for whatever reason, this possibility is very, very unlikely and thus you have knowledge that there is a table in front of you. Both “the possibility of error argument” and “the certainty argument” rely on the belief that because knowledge is sometimes fallible then knowledge is unobtainable for almost everything. In response to “the possibility of error argument” specifically, a fallibilist would argue that it is not a problem that knowledge may be erroneous. I think a fallibilist would say that as long as there are very strong reasons for the knowledge then it is indeed knowledge even though the possibility exists that it is untrue. Likewise, for the certainty argument a fallibilist would say that absolute certainty is unnecessary for knowledge and therefore it is possible to know things.

Part 4: I do like Feldmans response of falliblism to skepticism. I don’t know any better arguments you could make against the skeptic. Granted, I don’t think falliblism totally defeats skepticism for a few reasons. Falliblism says that the skeptic has interpreted the rules of knowledge incorrectly. A true skeptic believes that fallibility is fatal to knowledge while the fallibilist is perfectly content with knowledge being fallible. This is where the two schools of thought meet and ultimately disagree. However, falliblism does not completely defeat any of the skeptics arguments, it only says that they are playing by the wrong rules. According to the skeptics belief that falliblism is a problem, the skeptical arguments are perfectly reasonable. So, playing by the skeptics rules for knowledge (or by using their standard), their arguments are sound. Personally, I side with Feldman on this issue. I think that it is unreasonable to demand absolute certainty for knowledge. Like I mentioned earlier the scientific community does not rely on absolute certainty for their work and most scientists are happy with achieving a P-value of less than or equal 0.05 for their results. A P-value of 0.05 or 5% basically says that there is a 5% chance that the (significant) results you found happened by coincidence, or dumb luck (which would mean they are meaningless). So, 95% or less certainty usually works well for scientists and I don’t think absolute certainty is required to truly know that there is a table in front of me. Although, strictly speaking, we can never actually prove our hypothesis, we can only disprove the null hypothesis (which is the default position in a scientific study that claims there is no relationship between the subjects and whatever variable you are testing for). It is also important to distinguish between the common interpretation of skepticism and the epistemological meaning of the word. I think it is appropriate to say that most scientists are at least a little bit skeptical of new scientific discoveries, as they should be. However, most scientists do not make the claim that knowledge in their field is literally unknowable (which is the epistemological meaning of limited skepticism). We live our everyday lives being fallibilists, and I think that is a good thing. Not much, if anything at all, would get done if we all acted in accordance with the skeptical view of knowledge. In my opinion I actually think the skeptic has very weak arguments. Again, they only work if we use their absolute certainty of knowledge standard. But besides this the arguments are kind of silly. I will try to dispel the alternative hypothesis argument to explain what I mean. The alternative hypothesis argument says that our evidence does not provide better reason to believe ordinary external world propositions (such as I have hands) than it does to believe some rival skeptical scenario (such as I’m a brain in a vat). If this is the case, then we need to withhold our judgment of having hands. I think this is a little far fetched because I think that I do have much better evidence for having hands than I do for being a brain in a vat who is having a handish-experience. The fact that I can see that I have hands makes me believe that I do indeed have hands. Maybe I’m being gullible. I understand that the skeptic would say, “but if you are a brain in a vat you would not know the difference, hence you can not know whether you have hands or not”. I think I’m using the immediate perceptual justification argument here although I think there is something more to my conclusion that I do have hands than that. Just because I perceive my hands and then have immediate prima facie (justifiable but fallible) knowledge about me having hands doesn’t dispel the fact that I may be a brain in a vat. My interpretation of the immediate perceptual justification argument may be misconstrued but I think it’s basically saying that because I see and feel that I have hands I now am correct in saying “I know I have hands”, just because this is my first immediate experience. I think it may be more simple in that it is just incredibly unlikely that I am a brain in a vat, or that some malevolent God has deceived me than to say “I have hands”. This is a position Bertrand Russell took, arguing that there are many cases in which our supposed knowledge is incorrect (ie. I am a brain in a vat) but the majority of these cases are incredibly unlikely compared to the proposition “I have hands”. It is a little bit like Occams razor with a twist. I think that the heart of the skeptic vs fallibilist argument has to deal with the fact that knowledge and the acceptable standard for knowledge are subjective. Not only are they subjective from person to person they also differ from situation to situation, making a unified theory of “a knowledge standard” a difficult and possibly meaningless thing to do.


The Philosophical Works of Decartes, translated by Elizabeth S. Haldane (Cambridge University Press, 1973), Pages 145-6.

Epistemology, Richard Feldman, (Pearson Education, 2003), Page 122.


About ben james

"The stars keep me up at night" -some song I heard one time Human. Studying the intersection of Neuroscience and Computation. Wanna be (astro) physicist.
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