Many of us have encountered both our innate ability to make quick
judgements and our ability to have drawn out deliberate thought. Daniel Kahneman explores both of these abilities to a depth reserved for research psychologists.
Long story short - deliberate thinking is hard. Our brains try not to do it and will often allow us to feel like we're thinking deeply about something when really we're filtering through a lot of snap judgement information.
While quick judgements have their place and allow us to do a multitude of complex things, like getting a read on a person we're talking to, they're not great for areas where we need a truly scientific\disconnected approach. Like analyzing an investment or grading student papers.
Kahneman's book is definitely worth a read. It offers some great insights into how our minds work and gives us some fairly insightful takeaway - especially for those of us that like to hack our wetware.