- personal experience (human perceptions are iffy)
- experience of people you know (even more unreliable)
- experts (they work for money, not truth)
- scientific studies (correlation is not causation)
- common sense (a good way to be mistaken w/ complete confidence)
- pattern recognition (patterns, coincidence, & personal bias look alike)
the nearest we can get to the truth is Consistency. look for confirmation on at least two of the dimensions listed.