What you don't know doesn't exist (?)

If we can understand the nature of the building blocks, than we can understand the larger structures or organisms they create. Any thing is the sum of its parts.

This is the standard scientific methodology and it has brought us to astounding new heights of understanding. But with this understanding often comes an overconfidence of our own knowledge and the pool of "what we don't know, we don't know" shrinks in our mind (but only in our mind, unfortunately).
- And so we ignore the anti-oxidants in fresh fruits and focus on getting the necessary vitamins. - We focus on rising real estate prices and stock markets and ignore rising debt levels.
- We focus on enemy countries and ignore the sub-state terrorist groups.

It's natural to focus on what we can see, but obviously not always effective: like the joke of the man on a dark parking lot looking for a lost cell phone - but only looking for it in a tiny corner where the street lamp shines.

Taking a holistic approach, as oppose to a reductionist one is not without it's problems too, however. As you then have to swallow all of the mythology behind un-proven causes and effects to make sure you happen to eat those ant-oxidants you didn't know existed. It's not unsurprising that there's a lot of interesting questions to answer at this intersection.

Perhaps it's just my short memory or anecdotal evidence, but there appears to be an increasing acceptance of a blend of reductionist & holistic approaches in a variety of different disciplines:

Food & health: The whole foods movement (The Omnivores Dilemma)
Psychology: The behavioral psychology movement (Blink, Nudge)
Economics & Finance: acceptance of randomness (The Black Swan)
Exercise: The cross-fit movement

(I'm not sure about political science, TSA certainly hasn't learned anything about the lack of predictability in security threats.... why are we still confiscating little bottle of water?)