How I justify what I know

Looking at our different sources of knowledge, pragmatically

Photo by Siora Photography on Unsplash

In my previous post, I looked at knowledge from a 'subjective, inside perspective'. The focus was on what separates belief from knowledge, considering the practical role that knowledge plays in our lives. Given our limited time and energy, "we need a stock of reliable information about the world that we can act on without needing to think about it." My thesis was that knowledge, from the inside perspective of the knower, is what we put in that necessary stock of reliable information. That is, anything we trust enough to rely on without worrying about it.

Most of our knowledge, in these terms, is highly practical. It's about how to navigate our environment, what we can and can't eat, who we can trust, how to do our jobs and so forth. If we had to stop and figure out what is, or isn't, safe to eat from scratch every time we were hungry we'd never have time to do anything.

To tie this back to the traditional philosophical approach that sees knowledge as a version of 'justified true belief', this analysis effectively focused on what counts, from the inside perspective, as a 'true belief'. One key conclusion was that knowledge only needs to be true enough for us to act on it without worry. For example, I don't need a detailed and perfectly accurate knowledge of food toxins to be able to eat and stay healthy: the consequences for getting it somewhat wrong are almost always less severe than not eating.

Nevertheless, there is an element of this account that needs to be filled in - when is our knowledge justified. Given the focus here is on the 'subjective, inside perspective', we are not so interested in objective standards of justification. Instead, we need to focus on how, in practice, we decide different beliefs are sufficiently reliable to act on them. This varies according to different types of belief and so we need to consider different sources of knowledge, and what factors lead us to take that information as reliable. As a reminder, our knowledge is made up of theories and other plural structures. It isn't simply individual pieces of information.

Where does my knowledge come from?

The most obvious, and foundational, source of knowledge is personal observation and testing. We put a great weight on this sort of knowledge. "I saw it with my own eyes", for example, is a claim to reliable and trustworthy knowledge that is hard to argue against. And it is deeply wired into us as humans. Little children spend lots of time poking, banging, tasting and feeling all sorts of things around them to observe, test and therefore understand the world.

A second source of knowledge we all rely on is personal reasoning and problem solving. These are the things we have figured out ourselves and we take to be true - but which we haven't tested or cannot test, at least not yet. "I've figured it out and now I know why/who/that...." is a common type of claim that captures this idea. It could be anything from why I don't feel 100% today to global geo-politics, depending on our interests and confidence. This is the typical pattern of abductive reasoning that we employ - we put the pieces together to come up with the best explanation, which we then - should but don't always - test.

However, we live in a vast world and each one of us is limited in time, space, and energy. There is a wide variety of things we each know - that is, a lot of different sorts of beliefs about the world that we are willing to trust and act on - that go well beyond what we can individually observe, test or figure out.

Much of our knowledge comes from trusted sources of authority. We rely on the authority of other people that we trust, for whatever reason, and take what they tell as us reliable knowledge. The authority could be a parent, friend, teacher, a book, the 'internet' or some other source we take as an expert on the topic. This is a highly energy efficient approach for us humans as we cannot figure out everything for ourselves.

It also enables us, as highly social creatures, to know more as a collective than any individual within the group. Almost all of my knowledge of science, other countries, politics, computers and many other things comes from a trusted source of authority. I haven't looked into these things myself and so I, quite sensibly, take other sources of authority as definitive.

There is one less obvious source of knowledge that is easy to overlook. There is a range of knowledge that we each absorb from our environment. This is information that we take as reliable but we've never thought about it or had anyone tell us it is the case. A practical example might be that I know the new bar that has opened in town is a great place to visit, not because I've been there, thought about it or had anyone tell me it is great. Instead, I have just heard people talking about what happened and people keep making plans to have events there. I will likely act on that knowledge without any worry, even though it is just something I've absorbed without really thinking about it.

Less immediate examples of this are the range of cultural assumptions that we have all absorbed just from growing up in a particular time and place. These are rarely explicitly taught or explained, we just absorb them from everyone around us and think or act as if they are true.

This list of four different sources of knowledge may not be exhaustive. I’ll be interested if readers can identify ones I have missed. Moreover, in practice, these different sources of knowledge are not cleanly separated and we often use them together. I might rely on the information from an authority to figure something out (perhaps friendship dynamics or why my computer isn't working), which I then later test. But they are different sources that involve different types of justification for why we take a belief as trustworthy.

If I want to assess the validity of any information I count as knowledge, I need to understand what source I have relied on and then consider whether it is a reliable source, or combination of sources. Each of these four are, at times, legitimate sources of knowledge, at least in the sense we all use them to build our reliable stock of information, but they are all also defeasible. None of them is always reliable and correct.

Patterns of justification

Given that, on my account, we have a range of different sources of justification for knowledge that work differently, it would be useful to understand how they fit together. Is there a hierarchy of sources? Do we slot all of them into some kind of coherent network or structure? I doubt such a unified theory is possible and instead see my stock of knowledge as a patchwork of overlapping but not fully coherent theories, facts, pictures and models.

My knowledge about cooking, for example, is not systematic and also doesn't seem closely connected to anything I know about cars. However, from the inside practical perspective, it doesn't matter so much how our knowledge fits together. What matters is that we trust it when we need to act.

That said, how we put together different types and sources of knowledge is not simply haphazard and unordered. Here are some initial observations about principles that underpin some order.

• All else being equal, we each trust personal observation and testing over other sources. This reflects the practical point that we need knowledge to live our daily lives.

• There is a connection between the content of the knowledge and its source. For information closer to daily life, we rely more on personal observation and reasoning whereas we tend to rely more on authorities about things further removed. I'll rely on an academic expert for knowledge about quantum mechanics, but not for information about where I live.

• The connections and patterns of justification we accept often reflect who or what we trust in general, rather than any objective epistemic merits. I will often trust the authority of a good friend over someone I don't know, even if the stranger has, objectively, more reliable claims to epistemic authority.

• Our justification for unrelated pieces of information may be connected if they come from the same source. So I might discount what I thought I knew about various celebrities love lives and the structure of financial markets, to pick a random example, if I had relied on the same person for my knowledge of both and now no longer trust them.

For each of these, you can probably imagine situations where these principles are entirely appropriate and others where they will lead us astray. However, they all make pragmatic sense given the role of knowledge in enabling us to live successfully as social creatures.

Pragmatism often rules

For better or worse, when considering what information we take as reliable, pragmatic life considerations sometimes matter more than pure truthfulness. In fact, there are situations where we can end up with practical justifications for taking some kinds of information as reliable, irrespective of whether we think it is true.

One example is when we are dealing with a socially created reality, such as money. In a deep sense, it is hard to say whether money really has inherent value beyond the material it is made out of. In our daily lives, however, money clearly does have value and we should act as if it does without worry. Of course, everyone treating money as having value creates the confidence and conditions by which money does have that (pragmatic) value.

Another example is membership of certain types of social groups that all agree that certain theories or information are knowledge. You can't, for example, belong to some academic disciplines without accepting practical knowledge that other disciplines reject. The same dynamic holds with various groups of sports fans or, at the extreme, with religious and political cults. In these cases, if belonging to those groups is really important to you as an individual for some reason, it can be a rational pragmatic decision to accept certain beliefs as fully reliable regardless of whether you think they really describe the world.

Decisions like this may make pragmatic sense, yet there is a trade-off between successful life now and the longer term reliability of knowledge. Any way in which our knowledge, our stock of reliable information, is inaccurate as a depiction of the world increases our chances of things going wrong.

Yet it is also a trade-off we all make. There are many situations where we accept something now without really confirming accuracy. The reasons why we accept things into our reliable stock of information are messy, contingent and rarely completely justified. One consequence is that we need to remain humble about what we know and keep in mind how we get it wrong. A second is that we need to think seriously about the process by which we can, and should, change our mind. That will be the topic of the next post.