There are obvious benefits to be gained from the study of logic: heightened ability to express ideas clearly and concisely, increased skill in defining one's terms, enlarged capacity to formulate arguments rigorously and to analyze them critically. But the greatest benefit, in my judgment, is the recognition that reason can be applied in every aspect of human affairs.

Tens of thousands of students have learned to be more discerning at constructing and evaluating arguments with the help of Patrick J. Hurley. Hurley’s lucid, friendly, yet thorough presentation has made A CONCISE INTRODUCTION TO LOGIC the most widely used logic text in North America. In addition, the book’s accompanying technological resources, such as CengageNOW and Learning Logic, include interactive exercises as well as video and audio clips to reinforce what you read in the book and hear in class. In (...) short, you’ll have all the assistance you need to become a more logical thinker and communicator. Important Notice: Media content referenced within the product description or the product text may not be available in the ebook version. (shrink)

“Absence of evidence isn’t evidence of absence” is a slogan that is popular among scientists and nonscientists alike. This article assesses its truth by using a probabilistic tool, the Law of Likelihood. Qualitative questions (“Is E evidence about H ?”) and quantitative questions (“How much evidence does E provide about H ?”) are both considered. The article discusses the example of fossil intermediates. If finding a fossil that is phenotypically intermediate between two extant species provides evidence that those species have (...) a common ancestor, does failing to find such a fossil constitute evidence that there was no common ancestor? Or should the failure merely be chalked up to the imperfection of the fossil record? The transitivity of the evidence relation in simple causal chains provides a broader context, which leads to discussion of the fine-tuning argument, the anthropic principle, and observation selection effects. (shrink)

Rumors, for better or worse, are an important element of public discourse. The present paper focuses on rumors as an epistemic phenomenon rather than as a social or political problem. In particular, it investigates the relation between the mode of transmission and the reliability, if any, of rumors as a source of knowledge. It does so by comparing rumor with two forms of epistemic dependence that have recently received attention in the philosophical literature: our dependence on the testimony of others, (...) and our dependence on what has been called the ‘coverage-reliability’ of our social environment (Goldberg 2010). According to the latter, an environment is ‘coverage-reliable’ if, across a wide range of beliefs and given certain conditions, it supports the following conditional: If ~p were true I would have heard about it by now. However, in information-deprived social environments with little coverage-reliability, rumors may transmit information that could not otherwise be had. This suggests that a trade-off exists between levels of trust in the coverage-reliability of official sources and (warranted) trust in rumor as a source of information. (shrink)