Jach's personal blog

(Largely containing a mind-dump to myselves: past, present, and future)
Current favorite quote: "Supposedly smart people are weirdly ignorant of Bayes' Rule." William B Vogt, 2010

Child Labor

I'll come right out with it -- I don't think child labor is evil. For reference, I think you're a child if you're under the age of 14. Aspects of child labor I think are evil are unsafe working conditions and a trade of a child's education for a small amount of family income. That last aspect is easiest to explain: education is important, especially in the early years. Kids should be acquiring knowledge and having fun during this time, and if any of them are working it should be because they want to (for the work itself or for the money in order to buy something they want), not because their parents are poor. Any money a child earns should legally be theirs -- banks should make it easy to open an account entirely in the child's name with no adult supervision or access. I think work hours generally ought to be part time only (less than 25 hours a week), and between 14-16 that restriction is lifted during the summer months between school years. At the age of 16 I don't really see an important distinction with an 18 year old in terms of being able to join any area of the adult work force.

There are areas in the adult workforce that are unsuitable for children, and arguably for that transition period between 14-16 as well. Coal mines are by their nature unsafe. (As such it's actually not that bad compensation-wise, and even as a laborer you can still expect benefits.) Besides the safety concerns, the various jobs coal mining entails also typically require adult intelligence and adult physical fitness. Indeed the laborer position linked to wants candidates 21 years or older. (I have no problem with companies having age restrictions for their jobs -- if they want to exclude a certain segment of the market by choice, fine. But I think a lot of companies refuse to hire less-than-18 year olds (and especially less-than-16 year olds) simply due to legal complications.)

WW2-style sweat shops with lots of dangerous finger-chopping machines are also no place for a child. Even modern assembly plants aren't really suitable from a safety perspective. Simpler assembly line jobs like sorting or picking out defective food products requires an ability to focus on such an uninteresting activity for hours which most children simply do not have. (Also an awareness of one's cleanliness.)

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Correlation is evidence of causation

I've been bringing the title line out frequently for the past few years in response to people saying the somewhat true phrase "correlation does not imply causation", or the true phrase "correlation is not causation" which they've been indoctrinated by fraudsters protecting Big Tobacco.

When asked for a proof, I often just link to this page: It's the simplest and easiest to understand version I've come across. But I think it's sort of missing a final step, and a longer proof will fill that in.

In order to prove the title statement, we have to back up a bit and ask about what evidence is, and before we do that we have to ask about what belief is. Or rather, we don't really need to define what they are so much as how to measure them. Bets are a way of measuring your confidence and certainty of your beliefs, and odds ratios and other aspects of betting can be expressed through probability theory, so your beliefs being true can be expressed using probability theory as well. (If you're interested in non-betting-based foundation for probability theory governing beliefs, see Jaynes. If you're interested in representing uncertainty of several "flavors", see Goertzel.) So if we have a probability for a belief, and we encounter a new piece of evidence, then that will either raise or lower the probability of the belief depending on whether it's evidence for or against. Formally, if some fact A is evidence for belief B being true, that means that the probability of B being true is greater if A is true than if A is false. In math, $$P(B|A) \gt P(B|\overline{A})$$ means A is evidence of B.

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