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

Why Should I Care?

You're talking to someone about something, and at a pause in the conversation, they say "Why should I care?" What do you usually do? Maybe you'll reply "...I've been giving you many reasons thus far, have you even listened at all?" Or you might just stop talking altogether, or you might reiterate, or you might threaten them, or...

Here's something different you could say. Say: "Why shouldn't you care?" If they need more elaboration on that, which indeed they may, you can continue with the following.

It has been well-documented in numerous psychological studies that humans have a natural tendency to accept as true anything they read, and that it takes a mental effort to consider it and reject it as false. Put into statistical terms, humans look at a piece of information, and they think "The null hypothesis is that this information is true, thus the alternative hypothesis is that this information is not true, aka false." It is their job to provide enough evidence in favor of the alternative to reject the null as a false statement. If I read "2+2=3", I would automatically think "Null: 2+2=3, Alternative: 2+2 =/= 3. Reality has consistently shown time and time again that 2+2=4, therefore I have a huge mountain of evidence that I can reject the null as false, and say with near-certainty that 2+2 =/= 3."

The above is how court cases work by the way. The defendant is presumed innocent until proven guilty; that is, the null is that they are innocent, the alternative is that they are guilty. Note that it's not anyone's job to prove innocence, the null, which is assumed true until there is enough evidence to persuade a rational person otherwise. But also note that if you can't gather enough evidence to reject the null, that doesn't necessarily mean that the null is true. It just means you lack enough evidence to say it is false. This is shown in court cases where you're pretty sure this person killed this other person, but they have a twin, so there's enough doubt because you don't have good enough DNA evidence to distinguish the two so the defendant has to go free. The worst mistake you could make, in statistics and in a trial, is convicting an innocent person: rejecting the null as false when the null is in fact true.

So back to the original response to the question of this topic. "Why shouldn't you care?" Let the null hypothesis be "caring", and let the alternative hypothesis be "not caring". Therefore it is the job of the person with whom you're speaking to provide enough evidence for why they shouldn't care.


"African children are starving." (Implying that the other should do something.)

"Why should I care?"

"Why shouldn't you care?"

"Hmm. Because my needs come before everyone else's except my wife whom I love more than my life, giving an African child a fish isn't going to feed him for more than a day, I don't have the time or desire to go teach a small handful how to fish, nor do I wish to pay someone to do it for me because I think our teachers should stick here. It may be a significantly larger challenge to teach all of Africa and bring them to America's level of technology and so on compared to teaching Americans even more and ending up with nanotech, which we then use to replicate food essentially for free and say goodbye to hunger and poverty everywhere forever. It is on these grounds that I reject the hypothesis that I should care as false, and conclude with high confidence that I shouldn't care."

"...But what about helping your fellow man?"

"I haven't said anything against that as taken in the literal sense."

I think it'd be a lot better if everyone adopted a system like this, where one actually makes conscious decisions about things using evidence. Also, let people in on this, so instead of:

"Why shouldn't you care?"


"Bah! Here's why you should care!"

A proper response in this scenario would be "I guess you'll just have to care then until you can find a reason not to."

Finally, to clarify why you should initially choose "caring" as the null instead of "not caring" as the null, this is based on the observation that humans naturally take information as true before rejecting it. Thus if someone is talking in a persuading manner trying to get you to care, you should default to care and then if you think you shouldn't care find a reason why. And if you're trying to convince someone to care, and they give you evidence why not to care and reject caring, and you believe it is very weak, you can do another hypothesis test to see if the evidence they gave is even any good or not.

In the above largish example, had I instead said

"I shouldn't care about African children because they're black"

then that is pretty weak evidence, and the null shouldn't have even been rationally rejected in the first place. But if I said I rejected it anyway, you would first say

"That was poor evidence to reject the null, so I think you should provide more evidence,"

and then continue,

"But I'll play your game, let's see if your evidence is valid. Let the null be that your evidence is valid, that the color of skin alone is reason to not care; therefore the alternative is that your evidence is not valid, that the color of skin alone is not reason to not care. I have a significant pile of evidence here that says color doesn't matter significantly. If it did, then black people themselves wouldn't care about themselves or other blacks purely on the grounds that they're black."

And so the former evidence is tossed out, and the other person must try to find better evidence for why they shouldn't care.

I hope I wasn't too confusing in this (I may have used too many pronouns leading to confusion). If I was, let me know.

Posted on 2009-06-12 by Jach

Tags: math, philosophy, rationality, statistics


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