But there are plenty natural-occuring effects that can and do hamper your ability to make logical decisions. Aforementioned states - like when you're panicked or otherwise threatened most certainly affect decision making progress. That's why military and police go through elaborate training with a lot of discipline involved - without it, you rely on instincts alone and instincts and logical thinking don't really go hand in hand.
Strong emotions, too. Predetermined and unprovable beliefs. Simple ignorance of surrounding environment. Basic cranial trauma. Sufficiently annoying irritation of any kind. You don't need any help from drugs to hamper your logical thought process, trust me. Some types of stimulants might even help it.
I try and practice as much self discipline as I can, and while I'll admit that you can't always be in complete control, I like to minimize those opportunities. That is what I am trying to do, because I believe that logical decision making is far better than emotional ones. I haven't made an important emotional decision in quite some time.
And still, there's the sanity part. Where do you base your "sanity"? Considering your first rule, which is "live for yourself", or something, I already removed the post from the quote, it's pretty clear that you do not think everything should be devoted to the society.
But what we consider sanity generally doesn't go much further then following the societal expectations and norms, however idiotic from certain points of view they might be. A man who claims to see ghosts and believes that there is a conspiracy of musketeers out to get him is labeled as schizophrenic and "insane" because his actions and beliefs don't fit into the societal norms, and because he has no proof for, well, what he claims. A man who believes in an equally unprovable god (And no, everyone who's reading it, don't try to turn this into a religion thread unless you have objective proof) is accepted because similar beliefs have been a norm in said man's society for generations.
This isn't the best example, actually. A much better way would be to look at various social values.
