Internalism is a philosophical position that emphasizes the importance of internal states, such as beliefs and desires, in understanding knowledge and justification. According to internalists, the factors that justify a belief must be accessible to the individual, meaning that one should be able to reflect on and evaluate their own reasons for holding that belief. In contrast to externalism, which considers external factors like the environment or social context, internalism focuses on the individual's perspective. This approach is often discussed in the context of epistemology, the study of knowledge, and is associated with philosophers like Descartes and Kant, who emphasized the role of the mind in acquiring knowledge.