Philosophy 129 - 7.3.2 Theories of Justification

So far, we have looked at theories of justification as applied to individual beliefs. But beliefs are not always justified in isolation. Usually, the justification of one belief depends on the justification of other beliefs. I must be justified in trusting my perception to then be justified in believing that there is a bird outside of my office window. Thus, some theories focus on the structure of justification—that is, how a system or set of beliefs is structured. The theories on the structure of justification aim to illustrate how the structure of a system of beliefs leads to knowledge, or true beliefs.


Much of what a subject justifiably believes is inferred from other justified beliefs. For example, Ella justifiably believes the Battle of Hastings occurred in 1066 because her history professor told her this. But the justification for her belief doesn’t end there. Why is Ella justified in believing that her history professor is a good source? Furthermore, why is she even justified in believing that her history professor told her this? To the second question, Ella would reply that she is justified because she remembers her professor telling her. But then one can ask, Why is the reliance on memory justifiable? Justified beliefs rest on other justified beliefs. The question is whether the chain of justification ever ends. Foundationalists hold that justification must terminate at some point.

Foundationalism is the view that all justified beliefs ultimately rest on a set of foundational, basic beliefs. Consider a house. Most of what people see of a house is the superstructure—the main floor, columns, and roof. But the house must rest on a foundation that stabilizes and props up the parts of the house people can see. According to foundationalists, most beliefs are like the superstructure of the house—the frame, roof, and walls. The majority of people’s beliefs are inferential beliefs, or beliefs based on inference. And according to foundationalism, all beliefs rest on a foundation of basic beliefs (Hasan and Fumerton 2016). One of Ella’s foundational beliefs could be that her memory is reliable. If this belief is justified, then all of Ella’s justified beliefs derived from memory will rest on this foundational belief.

But what justifies basic beliefs? If basic beliefs function so as to justify other beliefs, then they too must be justified. If the foundation is not justified, then none of the beliefs that rest on it are justified. According to foundationalism, the beliefs that make up the foundation are justified beliefs, but they are justified non-inferential beliefs. Foundational beliefs must be non-inferential (not based on inference) because if they were inferential, they would get their justification from another source, and they would no longer be foundational. Foundational beliefs are supposed to be where the justification stops.

What is a basic belief, and what are the reasons for thinking basic beliefs are justified? French philosopher René Descartes (1596–1650) was a foundationalist, and he held that people’s basic beliefs are indubitable (Descartes 2008). An indubitable belief is one that cannot be mistaken. Clearly, if the foundation is made of beliefs that cannot be mistaken, then it is justified. But why think that foundational beliefs cannot be mistaken? Descartes thought that whatever a subject can clearly and distinctly conceive of in their mind, they can take to be true because God would not allow them to be fooled. As an illustration of how some beliefs might be indubitable, recall that knowledge by acquaintance is direct and unmediated knowledge. Acquaintance is unmediated by other ways of knowing, including inference, so beliefs gained though acquaintance are non-inferential, which is what the foundationalist wants. Beliefs gained via acquaintance are also justified, which is why Russell deems them knowledge. As an example, imagine that you see a green orb in your field of vision. You may not know whether the green orb is due to something in your environment, but you cannot be mistaken about the fact that you visually experience the green orb. Hence, knowledge by acquaintance is a possible candidate for the foundation of beliefs.


Coherentism is the view that justification, and thus knowledge, is structured not like a house but instead like a web. More precisely, coherentism argues that a belief is justified if it is embedded in a network of coherent, mutually supported beliefs. Think of a web. Each strand in a web is not that strong by itself, but when the strands are connected to multiple other strands and woven together, the result is a durable network. Similarly, a subject’s justification for individual beliefs, taken alone, is not that strong. But when those beliefs are situated in a system of many mutually supporting beliefs, the justification grows stronger. Justification emerges from the structure of a belief system (BonJour 1985).

Within foundationalism, the justifications for some beliefs can proceed in a completely linear fashion. Ella believes the Battle of Hastings occurred in 1066 because her professor told her, and she believes that her professor told her because she remembers it and thinks her memory is justifiable. One belief justifies another, which justifies another, and so on, until the foundation is reached. Yet very few beliefs are actually structured in this manner. People often look for support for their beliefs in multiple other beliefs while making sure that they are also consistent. Figure 7.5 offers a simplified visual of the two different structures of belief.

The figure on the left, labelled “Belief Web”, displays many large dots arranged in an unorganized cluster, with several arrows extending from each dot to other dots on the grid, some nearby and others far away. The figure on the right, labelled “Linear Beliefs”, displays the same type of dots arranged in a diamond-like array. A single arrow extends from most of these dots, pointing to the dot nearest to it. The dot in the center has two lines, pointing to two near neighbors.
Figure 7.5 There are two different ways of conceptualizing belief structures: as a web of interconnected beliefs (left) and as a linear structure (right) in which foundational beliefs justify other beliefs, one after the other in a line. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Often, when we think of the justification for our beliefs, we don’t just consider the original source of a belief. We also think about how that belief fits into our other beliefs. If a belief does not cohere with other beliefs, then its justification appears weak, even if the initial justification for the belief seemed strong. Suppose you need to go to the bank, and on your way out the door, your roommate tells you not to waste your time because they drove by the bank earlier and it was closed. Your roommate’s testimony seems like enough reason to believe the bank is closed. However, it is a weekday, and the bank is always open during the week. Furthermore, it is not a holiday. You check the bank’s website, and it states that the bank is open. Hence, the belief that the bank is closed does not cohere with your other beliefs. The lack of coherence with other beliefs weakens the justification for believing what your otherwise reliable roommate tells you.

To be fair, foundationalists also consider coherence of beliefs in determining justification. However, as long as a belief is consistent with other beliefs and rests on the foundation, it is justified. But consistency is not the same thing as logical support. The beliefs that there is a bird in that tree, it is November, and a person is hungry are all consistent with one another, but they do not support one another. And for coherentists, logical consistency alone does not make a system of belief justified. Justification arises from a system of beliefs that mutually reinforce one another. Support can happen in many ways: beliefs can deductively entail one another, they can inductively entail one another, and they can cohere by explaining one another. Suppose I am trying to remember where my friend Faruq is from. I believe he is from Tennessee but am not sure. But then I remember that Faruq often wears a University of Tennessee hat and has a Tennessee Titans sticker on this car. He also speaks with a slight southern twang and has told stories about hiking in the Smoky Mountains, which are partially in Tennessee. That Faruq is from Tennessee can explain these further beliefs. Note that I can get more assurance for my belief that Faruq is from Tennessee by considering my other beliefs about him. When beliefs mutually reinforce one another, they acquire more justification.

Coherentism more naturally reflects the actual structure of belief systems, and it does so without relying on the notion of basic, justified, non-inferential beliefs. However, coherentism has weaknesses. One objection to coherentism is that it can result in circularity. Within a system of beliefs, any belief can play a roundabout role in its own justification. Figure 7.6 illustrates this problem.

Four boxes, labelled “A”, “B”, “C”, and “D”, arranged in a diamond array. An arrow points from A to B, from B to C, from C to D, and from D to A.
Figure 7.6 The circularly problem: Belief A entails belief B, and belief B entails belief C. Belief C entails belief D, and belief D entails belief A. The beliefs are coherent, and all support one another. However, each plays a role in its own justification. D justifies A, but A justifies D through B and C. Circularity results in the beliefs not having any support at all. If D essentially justifies itself, then it has no justification. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Another objection to coherentism is called the isolation objection. A network of beliefs can mutually explain and support one another, thus giving them justification. However, it is not guaranteed that these beliefs are connected to reality. Imagine a person, Dinah, who is trapped in a highly detailed virtual reality. Dinah has been trapped for so long that she believes her experiences are of the real world. Because of the detailed nature of Dinah’s virtual reality, most of her beliefs are consistent with and support one another, just as your beliefs about the real world do. As long as Dinah’s beliefs are consistent and coherent, she will be justified in believing that her experience is of real objects and real people. So Dinah has justification even though all her beliefs concerning the reality of her world are false. Dinah’s situation reveals an important feature of justification: while justification makes beliefs more likely to be true, it does not always guarantee that they are true. Justification is often fallible.

The content of this course has been taken from the free Philosophy textbook by Openstax