What does it mean to believe? We often say things like "I believe..." and "they think that..." But what do we really mean by a "belief"? It's notoriously tricky to define. For starters, we sometimes think of beliefs in binaries (true vs. false) and other times in probabilities (a 90% chance of coming true). We sometimes would be willing to bet on our beliefs ("I'll bet you $100 that New York City is not the capital of New York State"), and other times we wouldn't be willing to bet (e.g...