section_path: Structure
section_name: Structure
paragraph_text: Structure
  
  The structure of knowledge is the way in which the mental states of a person need to be related to each other for knowledge to arise. A common view is that a person has to have good reasons for holding a belief if this belief is to amount to knowledge. When the belief is challenged, the person may justify it by referring to their reason for holding it. In many cases, this reason depends itself on another belief that may as well be challenged. An example is a person who believes that Ford cars are cheaper than BMWs. When their belief is challenged, they may justify it by claiming that they heard it from a reliable source. This justification depends on the assumption that their source is reliable, which may itself be challenged. The same may apply to any subsequent reason they cite. This threatens to lead to an infinite regress since the epistemic status at each step depends on the epistemic status of the previous step. Theories of the structure of knowledge offer responses for how to solve this problem.
  
  Three traditional theories are foundationalism, coherentism, and infinitism. Foundationalists and coherentists deny the existence of an infinite regress, in contrast to infinitists. According to foundationalists, some basic reasons have their epistemic status independent of other reasons and thereby constitute the endpoint of the regress. Some foundationalists hold that certain sources of knowledge, like perception, provide basic reasons. Another view is that this role is played by certain self-evident truths, like the knowledge of one's own existence and the content of one's ideas. The view that basic reasons exist is not universally accepted. One criticism states that there should be a reason why some reasons are basic while others are not. According to this view, the putative basic reasons are not actually basic since their status would depend on other reasons. Another criticism is based on hermeneutics and argues that all understanding is circular and requires interpretation, which implies that knowledge does not need a secure foundation.
  
  Coherentists and infinitists avoid these problems by denying the contrast between basic and non-basic reasons. Coherentists argue that there is only a finite number of reasons, which mutually support and justify one another. This is based on the intuition that beliefs do not exist in isolation but form a complex web of interconnected ideas that is justified by its coherence rather than by a few privileged foundational beliefs. One difficulty for this view is how to demonstrate that it does not involve the fallacy of circular reasoning. If two beliefs mutually support each other then a person has a reason for accepting one belief if they already have the other. However, mutual support alone is not a good reason for newly accepting both beliefs at once. A closely related issue is that there can be distinct sets of coherent beliefs. Coherentists face the problem of explaining why someone should accept one coherent set rather than another. For infinitists, in contrast to foundationalists and coherentists, there is an infinite number of reasons. This view embraces the idea that there is a regress since each reason depends on another reason. One difficulty for this view is that the human mind is limited and may not be able to possess an infinite number of reasons. This raises the question of whether, according to infinitism, human knowledge is possible at all.