Ultimately, I'm pretty sure I "always thought that way". The following ideas and their implications have always been obvious to me: consequentialism, reductionism, thinking at the margin, trade-offs, cost-benefit analyses, expected value.
But perhaps a) arguing with my parents, b) suffering through school, c) living in a world of irrational people, and d) being bullied influenced me by motivating me to think more deeply about things (often out of frustration and spite; which I'm not proud of, but am saying because it's true).
A: When I was younger, I was a bit mischievous. I would get punished a lot by my parents (a big problem I had was that I didn't know how to lose). When I was punished, I would have to sit in my room with all my toys having been taken away from me. And as a little kid with ADHD, sitting in a room by myself with nothing to do was pretty uncomfortable.
I would say things like "Your statement depends on A, B and C, so let me present my counter arguments, and if I change your mind on A, B or C, you should change your mind on the larger point" (except I didn't have the vocabulary to say this clearly). Sometimes I would present a good case and disprove A & B... but they always refused to change their mind on the larger point. This infuriated me. Usually I wouldn't receive an explanation, but when I did, it'd usually be "I'm the authority" or "that's just the way it is". "Just the way it is" is a huge pet peeve of mind.
So I used to dream of being a lawyer. I fantasized about this magical place called a court room where a judge enforced basic logic and let me make my points without being interrupted.
B: I found school to be incredibly boring. Perhaps this boredom motivated me to use rational thinking as a tool to help me avoid the unpleasantness (similar to Dan Ariely, but obviously to a lesser extent). Although I didn't have the vocabulary, the ideas of consequentialism, terminal vs. instrumental goals, Lost Purposes etc. were obvious to me at a very young age. I'd think:
Why do I need to do well in school? Grades -> college -> job -> money -> happiness. So then, I should only pursue grades and other instrumental goals to the extent that they lead to my terminal goal(s).
The boredom and frustration also motivated me to question the educational system itself. When school would do something that made me unhappy, I'd question, "Does it actually make sense that they're making us do this?". I'd often conclude that the answer is "no", and I'd be motivated to think about it from scratch and figure out a better system. Maybe this deep thinking helped me develop intellectually?
C: More generally, we live in a world where the sanity waterline is pretty low and there's a lot of stupidity around us (ex. refusing to admit that trade-offs exist; refusing to think at the margin). If there wasn't as much stupidity around me, maybe I wouldn't have been as motivated to think deeply about things, and wouldn't have developed as much. But because it's there, I think I just generally was frustrated and wanted to think deeply about topics to prove once and for all that the stupid person I was dealing with was wrong.
What would have happened if I grew up in a world of sane people? Without the extra motivation that frustration and spite provided me with, would I have been happy to sit back and play video games? Maybe. Maybe not. At this point, I'm mature enough to be motivated by things like truth and altruism, but I'm not sure if my middle/high school self would have been.
D: There was a point in middle school where I fought back against a bully and lost every friend I had for doing so. At the time, I was socially conscious enough to be a bit traumatized. But soon afterwards, I started to question things. Why care about social value? Through what mechanism do friends actually bring joy? I think this just further molded me into someone who questions/thinks about everything.
Other: I was raised Jewish. I remember believing in God and the bible stories when I was really young, but at the same time being confused by them. It was weird). I believed that there was some old man in the sky, but it made no sense to me that he didn't have a physical form. How could anything not have a physical form? And how could he be so powerful if he didn't have a physical form? I think I remember deviating a bit in my beliefs because of these questions I had. I think I believed that God was real, but that he had a physical form and wasn't quite what they told me.
In the years before my Bar Mitzvah, I definitely didn't believe in religion anymore. I was annoyed that I had to go to Hebrew School. I was also annoyed that I had to practice for my Bar Mitzvah, but wasn't opposed to having the ceremony to get the presents.
I also remember a specific day in 10th grade World History. We were learning about some African cultures and the Gods they believed in. I remember being taught that they had different Gods to explain different phenomenas. Like a God of rain, God of thunder etc. At that point, it really hit me that when humans don't understand something, they're capable of just inventing an explanation and believing it. "How is there water falling from the sky? It must be The God Of Rain".
Note: I've noticed that calling people stupid is frowned upon here. In this situation, I'm trying to communicate that I spent a lot of time being frustrated with people, and that it may have motivated me to think more deeply about things than I otherwise would have, so the word seems appropriate.
And for what it's worth, I'm altruistic, I want people to be happy, but I'm a big believer in accountability, and when people act stupidly, I think it's appropriate to call them out on it. Myself included!! If I act in a way that isn't just misguided, but is genuin...
I'm reading Dan Ariely's book Predictably Irrational. The story of what got him interested in rationality and human biases goes something like this.
He was the victim of a really bad accident, and had terrible burns covering ~70% of his body. The experience was incredibly painful, and so was the treatment. For treatment, he'd have to bathe in some sort of disinfectant, and then have bandages ripped off his exposed flesh afterwards, which was extremely painful for him.
The nurses believed that ripping it off quickly would produce the least amount of pain for the patient. They thought the short and intense bursts of pain were less (in aggregate) than the less intense but longer periods of pain that a slower removal of the bandages would produce. However, Dan disagreed about what would produce the least amount of pain for patients. He thought that a slower removal would be better. Eventually, he found some scientific research that supported/proved his theory to be correct.
But he was confused. These nurses were smart people and had a ton of experience giving burn victims baths - shouldn't they have figured out by now what approaches best minimize patient pain? He knew their failure wasn't due to a lack of intelligence, and that it wasn't due to a lack of sympathy. He ultimately concluded that the failure was due to inherent human biases. He then became incredibly interested in this and went on to do a bunch of fantastic research in the area.
In my experience, the overwhelming majority of people are uninterested in rationality, and a lot of them are even put off by it. So I'm curious about how members of this incredibly small minority of the population became who they are.
Part of me thinks that extreme outputs are the result of extreme inputs. Like how Dan's extreme passion for his work has (seemingly) originated from his extreme experiences with pain. With this rule-of-thumb in mind, when I see someone who possesses some extreme character trait, I expect there to be some sort of extreme story or experience behind it.
But another part of me thinks that this doesn't really apply to rationality. I don't have much data, but from the limited experience I've had getting to know people in this community, "I've just always thought this way" seems common, and "extreme experiences that motivated rational thinking" seems rare.
Anyway, I'm interested in hearing people's "rationalist backstories". Personally, I'm interested in reading really long and detailed backstories, but am also interested in reading "just a few paragraphs". I'm also eager to hear people's thoughts on my "extreme input/output" theory.