The Problems of Philosophy

Empiricism is the philosophical theory that proposes that all knowledge is derived from sensory experience. Humans develop understanding through connections built over multiple experiences and sensory perceptions. Russell explains that both empirical knowledge and priori knowledge contribute to knowledge.

Epistemology is a branch of philosophy concerned with The Nature and Limits of Human Knowledge. Epistemology studies how humans gain knowledge, make sense of the world around them, and determine whether concepts are true or false. Russell develops a theory that is both intuitive and logical while pulling from various philosophical works in the field.

Idealism is a philosophical theory that proposes that reality only exists within the mind or is mental. Russell applies logical analysis to challenge idealism. He argues that physical objects exist outside the mind and that reality contains its own fundamental nature. However, this nature is unknowable to humans who experience the world through subjective experience.

Knowledge by acquaintance is one category of knowledge that Russell identifies that refers to a direct, immediate awareness of a physical object through sensory experience. Russell explains that all knowledge has a foundation of acquaintance. When a person looks at a tree, that person is engaging in knowledge by acquaintance.

Unlike the previous two terms, knowledge by description requires no interaction with a physical object. Humans gain knowledge by hearing the descriptions or facts provided by others. When a person reads about an event in the news, they gain knowledge by description.

Knowledge of things is similar to knowledge by acquaintance. This term describes humans’ knowledge about tangible objects in the physical world. Russell explains that even this rudimentary type of knowledge requires priori knowledge because a person must understand basic principles about space, properties, and nature to make sense of the external world. While knowledge of acquaintance refers to the immediate awareness of an object, knowledge of things is less direct, requiring a more nuanced understanding.

Russell uses “physical object” to describe items in the external world that are tangible. Humans gain knowledge about physical objects through knowledge by acquaintance. Physical objects have their own natures that are unknowable to humans.

This Latin term means “from what is later” and refers to knowledge that is gained through experience or observation. Although Russell does not use this word directly, he uses its inverse, priori. These two terms are often seen side-by-side in philosophical texts exploring the nature of knowledge as either rational or empirical.

This Latin term means “from what is earlier.” This concept references knowledge that requires no experience. Priori knowledge is innate, although Russell diverges from a traditional use of the word that suggests that babies are born with a comprehensive, innate understanding. Instead, Russell uses the word to describe a process of logic that humans use to make inductions and inferences. Russell challenges the philosophical branches that suggest that knowledge is either posteriori or priori.

Russell equates rationalism, which argues that logic and reason are the primary sources of knowledge, with priori knowledge. He proposes that humans’ ability to apply logic is a form of innate knowledge that, when combined with experience, forms all types of understanding.

Sensation is the experience of taking in raw sense data through sight, sound, taste, touch, and smell. Russell argues that sensation is the initial step toward knowledge.

Sense data is the information the mind collects from physical objects. For example, an apple can be experienced through sight, taste, smell, and touch. Each interaction with the senses produces certain knowledge within the mind. Russell explains that humans take in varying sense data, even when observing the same physical object. Therefore, sense data can only correspond with the physical object; it can never fully represent the nature of matter itself.