[trendoid]

Find (or create) lots of obese people or smokers or alcoholics focusing only on hand strength exercises. Then see how their life expectancy changes compared to obese people, smokers or alcoholics that didn't do those hand strength exercises.

[deltaonefour]

>Find (or create) lots of obese people or smokers or alcoholics focusing only on hand strength exercises.

It's clear you don't see it. You don't have to focus on smokers or alcoholics that's irrelevant.

But let's modify your statement to not include the fluff.

>Find (or create) lots of people who focus only on hand strength exercises.

Even when you remove the fluff the statement above still shows how you don't understand the dichotomy between correlation and causation. The experiment in the article can in fact be summarized by this statement:

>Find lots of people who focus only on hand strength exercises.

This statement cannot prove hand strength causes longer lifespan, you are right. However to test for causality is trivial. you simply need to do do this:

>(Create) lots of people who focus only on hand strength exercises.

It is the act of creation that forms the causative proof. Think about it.

If I took a random population and made them train for grip strength. Then I compared that groups lifespan to the overall lifespan of people I didn't make train for grip strength and I find that there is a correlation with longer life span for people who trained for grip strength...

Well I've just verified causation. There is literally no other conclusion. Try to come up with a scenario where the two factors are not connected causally. You can't.

By having the experimenters hand controlling the causative factor, you can prove correlation. If you are simply observing things with no control over experimental parameters, correlation is then impossible to verify.

It is the act of creation or controlling the experiment that allows for causation to be verified.

[trendoid]

> If I took a random population and made them train for grip strength. Then I compared that groups lifespan to the overall lifespan of people I didn't make train for grip strength and I find that there is a correlation with longer life span for people who trained for grip strength... Well I've just verified causation. There is literally no other conclusion.

What if the people you trained for grip strength also started taking care of their health in general (eg. eating better and moving more often), after starting your grip strengthening exercises?

[deltaonefour]

>What if the people you trained for grip strength also started taking care of their health in general (eg. eating better and moving more often), after starting your grip strengthening exercises?

If caring more for their general health was "caused" by grip strength training than grip strength training is still causative for increasing lifespan.

Think about it. Prescribing grip strength training in this case will indeed increase lifespan if what I said above were true. But the claim people are making here is that the correlation has no causative relation... that prescribing grip strength training WILL NOT cause lifespan to increase.

In fact, everything the article claims is true if the scenario you described is real.

You're thinking about direct causation which is hard to define. If running increases heart health which increases lifespan... which caused lifespan to increase? Heart health or running? The most elegant definition is to say both do. But then again being born is causative to increased lifespan as well but making a statement saying birth causes increased lifespan isn't a meaningful statement.

The nature of causation is a chain of events leading all the way back to the beginning of time. All events in that chain caused the most recent event in the chain. Reality is, in fact, made up of single tree of causative events and multiple linked chains, where ancestors in the tree are said to be causative.

Sibling nodes and events that don't have an ancestor relationship at best can only share a correlation (aka common ancestor).