Thinking Fast and Slow by Daniel Kahneman

Nietzsche and Freud agree, we are ignorant of ourselves. The idea became commonplace in the 20th century. It still is but it is changing shape. It used to be thought that the things we didn't know about ourselves were dark, emotionally fetid, sexually charged. This was supposed to be why we were ignorant of them; we couldn't face them so we repressed them. The deep explanation of our astonishing ability to be unaware of our true motives and to what was really good for us, lay in our hidden hang ups.
These days the bulk of the explanation is done by something else; the 'dual process' model of the brain. We no know that we apprehend the world in two radically opposed ways, employing two fundamentally different modes of thought; 'system 1' and 'system 2'. System 1 is fast, it's intuitive, associative, metaphorical, automatic , impressionistic and it can't be switched off. It's operations involve no sense of intentional control, but it is 'the secret author of many of the choices and judgements you make' and it is the hero of Daniel Kahnemans alarming, intelectually aerobic book.
System 2 is slow, deliberate, effortful. Its operations require attention. It takes over when things get too difficult. Its 'the conscious being called 'I'', and one of Khanemans main points is that this is a mistake. You are wrong to identify with system 2 for you are also and equally system 1. System 2 is slothful and tires easily, (a process called ego depletion) so it usually accepts what system 1 tells it. It is mostly right to do so as system 1 is pretty good at what it does; its highly sensitive to subtle environmental cues, asigns of danger and so on. It kept our remote ancesstors alive. It does, however, pay a high price for speed. It loves to simplify, to assume 'what you see is all there is' even as it gossips, embroiders and confabulates. Its hopelessly bad at the kind of statistical thinking often required for good decisions, it jumps wildly to conclusions and is subject to a fantastic suite of irrational biases and interference effects (the 'halo' effect, the 'florida' effect, framing effects, anchoring effects, the confirmation bias, outcome bias, the focusing solution and so on)
The general point about our self deception extends beyond the details of systems 1 and 2. We're astonishingly suseptable to being influenced by features of our surroundings. We don't know who we are or what we're really like, we don't know what we are doing or why we are doing it. That is system 1 exagewration yet true. Judges may think they make considered decisions based strictly on the facts of the case. It turns out that it is their blood sugar levels really acting in judgement. If you force your face in to a smile you'll find a joke funnier than if you force a frown. One great book on this is 'Strangers to ourselves' by Timothy D Wilson.
We hugely underestimate the role of chance in our lives. Analysis of the performance of fund managers over the longer term proves conclusively that you'd do just as well deciding on the roll of a dice. There is a tremendously powerful illusion that sustains managers in thier belief their results, when good, are down to skill. The fact remains that performance bonuses are awarded for luck, not skill.
In an experiment to test the 'anchoring effect' highly experienced judges were given a description of a shop lifting offence. They were then 'anchored' to different numbers by being asked to roll a pair of dice that had been secretly loaded to produce only two totals, three or nine. Finally, they were asked whether the prison sentence for the shop lifting offence should be greater or fewer months than the total shown on the dice. Normally the judges would have made very similar judgements, but those who had just rolled nine proposed an average of eight months while those who had rolled three proposed an average of only five months. All were unaware of the anchoring effect.
The same goes for all of us, we think we're smart. We're wrong. We're hopelessly subject to the 'focusing illusion' which can be conveyed in one sentence; 'nothing in life is as important as you think it is when you are thinking about it'.