Comment Pragmatist (Score 1) 210
For some great anecdotal evidence, look in the back of Popular science magazines where they print headlines from 25-75 years ago. There are doom and gloom ones (e.g. predicting '1984' type of developments) and overly optimistic (e.g., 'by 2000, we won't have to do housework because robots will be doing it for us'). I find that the truth is almost universally between the two extremes.
I also find that this view works extremely well when applied to the economy and politics as well (as in, Bush is not the devil incarnate in spite of numerous bad decisions, and Obama is not going to turn the nation into a socialist welfare state where we pay 60%+ in taxes -- nor is he going to fix our problems in the first 100 days of his presidency).
This view is especially helpful in light of discussions concerning exponential growth. It is easy to show trends that have continued for the past X years and then conclude that since numbers don't lie, this will continue for the next Y years. These arguments are easy to demonstrate and harder to refute (meaning it takes less technical knowledge to make them than to disprove them), making them widely used in persuasion.