 We engage in negative thinking to avoid highly complicated positive thinking. What is the probability of getting at least one head in ten tosses of a coin? Instead of directly computing the probability of this highly disjunctive positive event, we switch to a negative perspective. We first calculate the probability of a total absence of heads and then exploit the complement rule: Probability (at least one head) = 1 − Probability (no heads). An apt anagram of NEGATIVISM is TIMESAVING.