There are some great points here but I'm not entirely sold on the 'Right Brain Optimistic' , 'Left Brain Pessimistic' part. I'd say the Right Brain is often gre

There are some great points here but I'm not entirely sold on the 'Right Brain Optimistic' , 'Left Brain Pessimistic' part. I'd say the Right Brain is often great early warning mechanism for a lot of people (i.e. that gut feeling that something isn't right). If taken too far it would most likely be the source of phobias. It's like a 'black box probability engine'. Very powerful but difficult to debug. From what I've read the Left Brain is the 'communicator' as well as the 'logician'. I suspect this is the reason why discussion of probabilities, risk and 'expected returns' are often fraught with confusion - because the Left Brain doesn't really know how to process these things. The Left Brain prefers to round probabilities to 0%, 100% or 'unknown/50%'. It seems like many of the science/policy debates in the world (and on HN) are caused by people having different rounding criteria and starting probabilities.