One question I do have is what exactly is the importance of decision theories? [...] Are they applicable in real life situations or only in thought experiments?
One of the main functions of a good decision theory is to bridge the territory-map divide: by solving problems in your head, it shows you how to solve problems in the real world. You can identify a good decision theory when it works in theory and in practice. If a decision theory seems to work in practice, but is not describable in a precise language (e.g. "do what feels good"), it actually hasn't been well thought out and puts you at risk of being paralyzed when a very serious and very complex situation arises. On the other hand, if it only works in theory but is impracticable (e.g. "pray to Minerva for an omen"), it will be a waste of storage space in your head. In short, a decision theory should serve as a tool for you to manage your life.
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A list of some posts that are pretty awesome
I recommend the major sequences to everybody, but I realize how daunting they look at first. So for purposes of immediate gratification, the following posts are particularly interesting/illuminating/provocative and don't require any previous reading:
More suggestions are welcome! Or just check out the top-rated posts from the history of Less Wrong. Most posts at +50 or more are well worth your time.
Welcome to Less Wrong, and we look forward to hearing from you throughout the site!
Once a post gets over 500 comments, the site stops showing them all by default. If this post has 500 comments and you have 20 karma, please do start the next welcome post; a new post is a good perennial way to encourage newcomers and lurkers to introduce themselves. (Step-by-step, foolproof instructions here; takes <180seconds.)
If there's anything I should add or update on this post (especially broken links), please send me a private message—I may not notice a comment on the post.
Finally, a big thank you to everyone that helped write this post via its predecessors!