One: A Philosophical Problem Concerning Perception and Knowledge.- 1. Why Perception Does not Amount to Knowledge.- 2. Does Perception Under Normal Conditions of Observation Amount to Knowledge?.- 3. The Requirement that the Conditions be Known to be Normal.- 4. An Attempt to Avoid the Regress: The Sense-Datum Theory.- Two: The Argument from Perceptual Relativity.- 1. Exposition of the Argument.- 2. Evaluation of the Argument.- Three: The Argument from Causation.- 1. Some Ineffective Versions of the Argument.- 2. An Epistemological Version of the Argument.- 3. Psychological and Epistemic Immediacy: A Crucial Distinction.- Four: The Argument from Hallucination.- 1. Analysis of the Argument from Hallucination.- 2. A Reformulation of the Argument.- Five: The Causal Theory of Perception.- 1. General Formulation of the Causal Theory.- 2. The Analytic Thesis.- 3. Does the Causal Theory Imply that Physical Objects are Unperceivable?.- 4. The Justification Thesis (I).- 5. The Justification Thesis (II).- Six: Phenomenalism.- 1. Ontological Phenomenalism: Its Advantages.- 2. Ontological Phenomenalism: Its Paradoxes.- 3. The Linguistic Version of the Sense-Datum Theory and Analytical Phenomenalism.- Seven: Phenomenalism and the Causal Theory of Perception: A Combined Theory.- 1. Preliminary Considerations in Favor of a Combined Theory.- 2. The Adverbial Theory of Appearing.- 3. A Combined Theory.- 4. Epistemological Phenomenalism and 'Critical Cognitivism'.- 5. Epistemological Phenomenalism (I): The Entailment of Appear-Statements by Thing-Statements.- 6. Epistemological Phenomenalism (II): The Entailment of Thing-Statements by Appear-Statements.- Index of Names.- Index of Subjects.