2. Overoptimism amps up our other cognitive biases.

Much of the time that we think we’re thinking, we’re actually not, because much of our decision-making actually happens on a fast, automatic, and largely unconscious level. Thinking positively about future outcomes, in the absence of cues that would serve as a realistic basis for optimism, only amplifies our propensity for incorrectly seeing a single slightly positive or less negative result as “proof” of progress or an increased possibility of success (known as intermittent reinforcement); believing that we are above-average in our talents and abilities; focusing on what we have already invested toward a goal (known as the sunk-cost fallacy); and seeing what’s a really a complete miss as a “near win." Overoptimism increases our ability to hoodwink ourselves into thinking we’re making progress when we’re really standing still.

Optimism good. Overoptimism bad.