In the discussion on the last post on measurement, the definition of knowledge came up a few times. That’s dredged up long standing thoughts I have about knowledge, which I’ve discussed with some of you before, but that I don’t think I’ve ever actually put in a post.
The ancient classic definition of knowledge is justified true belief. This definition is simple and feels intuitively right, but it’s not without issues. I think the effectiveness of a definition is in how well it enables us to distinguish between things that meet it or violate it. In the case of “justified true belief”, its effectiveness hinges on how we define “justified”, “true”, and “belief”.
How do we justify a particular proposition? Of course, this is a vast subject, with the entire field of epistemology dedicated to arguing about it. But it seems like the consensus arrived at in the last 500 years, at least in scientific circles, is that both empiricism and rationalism are necessary, but that neither by themselves are sufficient. Naive interpretations of observations can lead to erroneous conclusions. And rationalizing from your armchair is impotent if you’re not informed on the latest observations. So justification seems to require both observation and reason, measurement and logic.
The meaning of truth depends on which theory of truth you favor. The one most people jump to is correspondence theory, that what is true is what corresponds with reality. The problem with this outlook is that only works from an omniscient viewpoint, which we never have. In the case of defining knowledge, it sets up a loop: we know whether a belief is knowledge by knowing whether the belief is true or false, which we know by knowing whether the belief about that belief is true or false, which we know by… Hopefully you get the picture.
We could dispense with the truth requirement, simply define knowledge as justified belief, but that doesn’t seem right. Prior to Copernicus, most natural philosophers were justified in saying they knew that the sun and planets orbit the earth. Today we say that that belief was not knowledge. Why? Because it wasn’t true. How do we know that? Well, we have better information. You could say that our current beliefs about the solar system are more justified than the beliefs of 15th century natural philosophers.
So maybe we could replace “justified true belief” with “currently justified belief” or perhaps “belief that is justified and not subsequently overturned with greater justification.” Admittedly, these aren’t nearly as catchy as the original. And they seem to imply that knowledge is a relative thing, which some people don’t like.
The last word, “belief”, is used in a few different ways in everyday language. We often say “we believe” something when we really mean we hope it is true, or we assume it’s true. We also often say we “believe in” something or someone when what we really mean is we have confidence in it or them. In some ways, this usage is an admission that the proposition we’re discussing isn’t very justified, but we want to sell it anyway.
But in the case of “justified true belief”, I think we’re talking about a version that says our mental model of the proposition is that it is true. In this version, if we believe it, if we really believe it, then don’t we think it’s knowledge, even if it isn’t?
Personally, I think the best way to look at this is as a spectrum. All knowledge is belief, but not all belief is knowledge, and it isn’t a binary thing. A belief can have varying levels of justification. The more justified it is, the more it’s appropriate to call it knowledge. But at any time, new observations might contradict it, and it would then retroactively cease to have ever been knowledge.
Someone could quibble here, making a distinction between ontology and epistemology, between what is reality, and what we can know about reality. Ontologically, it could be argued that a particular belief is or isn’t knowledge regardless of whether we know it’s knowledge. But we can only ever have theories about ontology, theories that are always subject to being overturned. And a rigid adherence to a definition that requires omniscience to ever know whether a belief fits the bill, effectively makes it impossible for us to know whether that belief is knowledge.
Seeing the distinction between speculative belief and knowledge as a spectrum pragmatically steps around this issue. But again, this means accepting that what we label as knowledge is, pragmatically, something relative to our current level of information. In essence, it makes knowledge belief that we currently have good reason to feel confident about.
What do you think? Is there a way to avoid the relative outlook? Is there an objective threshold where we can authoritatively say a particular belief is knowledge? Is there an alternative definition of knowledge that avoids these issues?