Is Knowledge Justified True Beilief?

Been awhile since we’ve posted, but I’ve been enjoying the heck out my course of epistemology, so I might as well share some of that love.

So what is knowledge? Well that’s a open question, but for the better part of the last 3 millennia one suggestion has been offered up. Possibly starting with Plato’s Theaetetus we’ve had the idea of Knowledge being justified true belief. The Idea looks like this.

  1. If p is true,
  2. You believe that p is true,
  3. and you are justified in believing p

then you know p.

Now there are all kinds of problem you might have with this definition of knowledge, but I’d like to see if anyone has thoughts, or wants to discuss the topic. If you do write a comment down below!


9 responses to “Is Knowledge Justified True Beilief?

  • Mallee Stanley

    From whose perspective is p true?


  • nuclearkumquat

    I think a bigger question to ask, in light of your definition, is how can we be certain we know some thing? If a proposition must be true for us to know it, then it follows that we must know it to be true for us to know it at all. The truth of any given proposition, however, is very hard to confirm or deny. I’m not sure if you’re familiar with Immanuel Kant’s objection to synthetic a priori judgements, but that seems to be a problem for this definition of knowledge. If we can’t be certain of the truth of any given proposition then it follows, from this definition, that we can’t be certain that we know anything at all.


  • Swarn Gill

    A number of cognitive scientists have made the argument that belief and learning are tied together, so I have no problem considering what I think is true is also knowledge and justified. However, I agree with the above that those same cognitive scientists would say that we also have a plethora of biases and so we are better off thinking that anything we know may not be 100% accurate, given our own limitations in conceiving reality. Although the scientific method gives us a tool to help us get closer and closer to knowing what is true, the problem really lies in how reliably we can say “p is true”. But providing we know the truth of “p” then we are justified in believing p is true. The amount of people who think a p is true (or most likely to be true), when it is not is really the problem. lol

    Liked by 1 person

  • paidiske

    I wonder if there is place for the idea of a margin of error? I mean something like, if p is true, and you believe something approximating to p (with justification), you have some knowledge of the truth even if it is imperfect knowledge.

    I am not trained in epistemology, though, so I have no idea if that would make the philosophers scoff!

    Liked by 1 person

    • hessianwithteeth

      Some would scoff, but many would agree that is a compelling path to tread. Modal logic and it’s practitioners would be your friend in that regard.


    • Sha'Tara

      My personal take: knowledge proper comes from personal experience and acceptance of that experience, i.e., not ascribing it to something esoteric outside of my experience, like, e.g., faith in some divine wizard who makes things happen for me. Seeking intellectual knowledge is climbing an ever-narrowing stairway to an ever-retreating ivory tower from which it becomes more and more difficult to share that “knowledge” with rank-and-file sentience. If I can put a “binder dundat” on it, that’s knowledge, always subject to change without notice for as was said, change is the one constant in the universe. If “knowledge” equals being able to certify something as true then that definition of knowledge is a chimera: no such thing as “the Truth” except in a completely closed mind. For me, it’s seek after experience and that experience becomes knowledge, not the other way around. I would also add that “beliefs” only subtract from knowledge, hence why I’ve formulated my approach to life as, “believe all things, believe IN nothing.” By “believe all things” I mean that anyone can believe anything they want, sharing that with me as passionately as they wish, and that won’t change anything to my understanding unless I can appropriate that belief and mesh it into my personal experience. If it doesn’t mesh, it’s water off a duck’s back.


  • equippedcat

    In the 60’s a fellow by the name of Edmund Gettier, came up with some cases where “JTB” seemed inadequate. The cases were based on the concept that although the belief may be correct, the reasons for that belief were invalid; that is, even though you believe the correct thing, the justification for that belief was wrong.

    And that leads me to a worse scenario. What if ‘p’ is NOT true, but there is no way to discern that? Then a person would think they know something because they believe something and feel justified in believing that based on invalid input. As far as they can tell, they have satisfied all 3 aspects of knowledge but actually only satisfied one aspect, and arguably the least important of the 3.

    Liked by 1 person

    • hessianwithteeth

      Indeed Gettier Cases are a lot of fun.I was thinking I might bring those up next, but I”m glad to see you know of them. I’ll need to find a paper my Professor told me about and share it. It’s about an amusing, if outlandish Gettier case. You’d probably enjoy it.

      I think you’ve outlined some of the arguments I find most compelling, but I’ll save my analysis for tomorrow after a few more comments roll in. (and my brain is refreshed).


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