I've written up a post offering a gentle, accessible introduction to anthropic reasoning! After writing my previous post on applying the anthropic principle to mathematical effectiveness, I realized three things:

1. Many people have a poor or non-existent understanding of anthropic reasoning
2. Many people who have some understanding of anthropics treat it as "separate magisterium" far away from everyday life
3. The existing guides on anthropics perpetuate this problem, making anthropics come across as more mystical and far-away than it actually is.

So hopefully having a "baby's guide" to anthropics can help alleviate this problem! If you or some other baby in your life is pondering difficult anthropic problems read (or send them) this guide! The guide covers:

1. Introduction to the anthropic principle

2. Reference Class tennis

3. Self-Indication Assumption

with worked examples from practical everyday life, as well as more advanced (toddler-friendly) topics:

1. How can someone use anthropics reasoning in everyday life?
2. Pedagogical notes
3. Population-weighted reasoning
4. SSA
5. Recommendations for further reading from Bostrom and Carlsmith to Tristan Cook's Grabby aliens model, and even relevant fiction

Excited for thoughts, suggestions for improvement, additional resources, and further feedback from the community!

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Baby Emma’s parents are waiting on hold for customer support for a new experimental diaper. The robo-voice cheerfully announces: "Our call center is rarely busy!" Should Emma’s parents expect a response soon?

Baby Ali’s parents are touring daycares. A daycare’s glossy brochure says the average class size is 8. If Ali attends, should Ali (and his parents) assume that he’d most likely be in a class with about 8 kids?

Baby Maria was born in a hospital. She looks around her room and thinks “wow this hospital sure has many babies!” Should Maria think most hospitals have a lot of babies, her hospital has unusually many babies, or something else?

For every room Baby Jake walks into, there’s a baby in it. Why? Is the universe constrained in such a way that every room must have a baby?

Baby Aisha loves toys. Every time she goes to a toy box, she always finds herself near a toy box with baby-friendly toys she can play with, not chainsaws or difficult textbooks on cosmology or something. Why is the world organized in such a friendly way for Aisha?

Baby Briar’s parents are cognitive scientists who love small experiments. They flipped a coin before naptime. If heads, they wake Briar up once after an hour. If tails, they wake Briar up twice - once after 30 minutes, then again after an hour (and Briar has no memory of the first wake-up because... baby brain). Briar is woken up and wonders to himself “Hey, did my parents get heads or tails?”

Baby Chloe’s “parents” are Kaminoan geneticists. They also flipped a coin. They decided that if the coin flip was heads, they would make one genetically enhanced clone and call her Chloe. If the coin flip was tails, they would make 1000 Chloes. Chloe wakes up and learns this. What probability should she assign to the coin flip being heads?