1. CHAPTER FIVE: THE SOURCES OF KNOWLEDGE P H I L O S O P H Y A Text with Readings ELEVENTH EDITION M A N U E L V E L A S Q U E Z

2. CHAPTER FIVE: THE SOURCES OF KNOWLEDGE P H I L O S O P H Y There are two common views regarding the sources of knowledge: rationalism and empiricism.

3. CHAPTER FIVE: THE SOURCES OF KNOWLEDGE P H I L O S O P H Y Rationalism states that some knowledge is based on reason rather than on sensory perception.

4. CHAPTER FIVE: THE SOURCES OF KNOWLEDGE P H I L O S O P H Y René Descartes was a rationalist concerned with discovering something that he could hold as true beyond any doubt. He concluded that no one could doubt that a human is a thinking being, that a thinking thing exists, that God exists, and that the world exists. All of this, he claimed, could be established by reason alone.

5. CHAPTER FIVE: THE SOURCES OF KNOWLEDGE P H I L O S O P H Y Empiricism states that all knowledge comes from or is based on sensory perception and is a posteriori.

6. CHAPTER FIVE: THE SOURCES OF KNOWLEDGE P H I L O S O P H Y John Locke held that objects have primary qualities that are distinct from our perception of them, such as size, shape, and weight. He also believed that they have secondary qualities that we impose on them, such as color, smell, and texture. We know the objective world through sensory experience, which is a copy of reality and which gives us our ideas of reality.

7. CHAPTER FIVE: THE SOURCES OF KNOWLEDGE P H I L O S O P H Y According to George Berkeley's subjectivism, we know only our own ideas. Carried to an extreme, this position can become solipsism, the position that only I exist and everything else is a creation of my subjective consciousness.

8. CHAPTER FIVE: THE SOURCES OF KNOWLEDGE P H I L O S O P H Y David Hume pushed Locke and Berkeley's empiricism to its logical conclusion. Arguing that all knowledge originates in sensory impressions, Hume distinguished between two forms of perceptions, impressions and ideas. Impressions are lively perceptions, as when we hear, see, feel, love, or hate.

9. CHAPTER FIVE: THE SOURCES OF KNOWLEDGE P H I L O S O P H Y Ideas are less lively perceptions; they are reflections on sensations. Hume denied that there is any logical basis for concluding that things have a continued and independent existence outside us. He denied the possibility of any certain knowledge, arguing that both rationalism and empiricism are inadequate to lead to truth and knowledge. He is thus termed a skeptic.

10. CHAPTER FIVE: THE SOURCES OF KNOWLEDGE P H I L O S O P H Y Immanuel Kant's transcendental idealism, an alternative to empiricism and rationalism, distinguishes between our experience of things (phenomena) and the things as they are (noumena). The mind, claimed Kant, possesses the ability to sort sensory experiences and posit relationships among them. Through an awareness of these relationships, we come to knowledge.

11. CHAPTER FIVE: THE SOURCES OF KNOWLEDGE P H I L O S O P H Y Inductionism is the view that all science is based on the process of sensory observation, generalization, and repeated confirmation. This process is often used to establish scientific laws, and simplicity is one criterion for choosing among competing generalizations.

12. CHAPTER FIVE: THE SOURCES OF KNOWLEDGE P H I L O S O P H Y The hypothetical method view says that science is also based on the creative formulation of hypotheses whose predictions are then tested and used to guide research. Karl Popper argued that falsifiability is a criterion of scientific theories.

13. CHAPTER FIVE: THE SOURCES OF KNOWLEDGE P H I L O S O P H Y Thomas Kuhn argued that scientific theories are those that are widely accepted by a community of scientists. They are the basis of paradigms that guide research but that are abandoned in a scientific revolution, when too many anomalies appear that cannot be accounted for by the paradigm. Scientific theories must be accurate, consistent with other widely accepted theories, capable of explaining phenomena other than those they were developed to explain, capable of organizing phenomena that were previously thought to be unrelated, and fruitful insofar as they generate new research and new discoveries.