I'm not exactly new - I've been lurking for a long time, soaking up all the glorious sanity from a few sequences and a lot of individual essays. And I've made a few comments. Still, I'd like to introduce myself properly. : )
(The main reason for this is that I think I need to lighten up and stop thinking of this site as a Sacred Order of Pedestaled Supergeniuses where my humble intellect doesn't belong, in order to grow.)
Insofar as anyone wants to know, I'm a 24 year old fellow, I have a Master's degree in linguistics since last year and now I spend my days as a humble translator. Somehow I fare better with intellectual pursuits if they're a hobby rather than how I make a living.
I think I'm a rationalist for one okay reason and one rather unflattering one.
The okay reason is that I've lived with a psychological diagnosis since I was... maybe 8 or so, so from very early on I've been quite aware of the fact that my brain is broken and needs fixing. I think I made more thinking errors than other people, but also importantly I made unusual thinking errors that stood out. My gut instincts clearly leading me in the wrong direction a lot, my feelings often being noticeably fickle and inconsistent. Rationalism has always helped me cope with the confusion caused by that sort of thing.
The rather unflattering reason is that it makes me feel smart. I'm not proud of it, but I'm not going to lie. I have a long-standing horrible habit of trying to win debates to aid my self-esteem. Entering controversial discussions and melodramatically grand-standing in them is a guilty pleasure I'm still working on cutting the heck out.
(Not to worry, though - I wouldn't drag down the wonderful level of this place with that sort of silliness.)
I tend to ramble a bit in my writing, and I can only hope to approximate the level of clarity you'll be used to. But I do my best to improve. : )