Time Travel Time travel is commonly defined with David Lewis’ definition: An object time travels if and only if the difference between its departure and arrival times as measured in the surrounding world does not equal the duration of the journey undergone by the object. For example, Jane is a time traveler if she travels away from home in her spaceship for one hour as

Metaphysics of Science Metaphysics of Science is the philosophical study of key concepts that figure prominently in science and that, prima facie, stand in need of clarification. It is also concerned with the phenomena that correspond to these concepts. Exemplary topics within Metaphysics of Science include laws of nature, causation, dispositions, natural kinds, possibility and necessity, explanation, reduction, emergence, grounding, and space and time. Metaphysics

Robert Boyle (1627—1691) Robert Boyle was one of the most prolific figures in the scientific revolution and the leading scientist of his day. He was a proponent of the mechanical philosophy which sought to explain natural phenomena in terms of matter and motion, rather than appealing to Aristotelian substantial forms and qualities. He was a champion of experimental science, claiming that theory should conform to

Persistence in Time No person ever steps into the same river twice—or so goes the Heraclitean maxim. Obscure as it is, the maxim is often taken to express two ideas. The first is that everything always changes, and nothing remains perfectly similar to how it was just one instant before. The second is that nothing survives this constant flux of change. Where there appears to

The Value of Art Philosophical discourse concerning the value of art is a discourse concerning what makes an artwork valuable qua its being an artwork. Whereas the concern of the critic is what makes the artwork a good artwork, the question for the aesthetician is why it is a good artwork. When we refer to a work’s value qua art, we mean those elements of

Two-Dimensional Semantics Two-dimensional (2D) semantic theories distinguish between two different aspects, or ‘dimensions’, of the meaning of linguistic expressions. Many other theories identify the meaning of an expression with a dependency of its extension on the state of the world. (The extension of a sentence is its truth-value, and the extension of a sub-sentential expression is the object or objects it applies to.) Consider the