Making correlations is an inherent part of the behavior of all intelligent animals: it is how we learn, and it is a key to our survival. If touching a switch causes immediate pain, and touching it again has the same effect, almost all animals will not only stop touching said switch, but will always fear and avoid it. Learning associated with negative stimulation is the strongest when it involves food, a behavior that likely evolved to prevent poisoning (before language allowed us to communicate information about which plants and animals we should eat, and which we should not). This response is so engrained, that often people who become violently ill will not be able to eat whatever they consumed prior, even if they know rationally that the food itself was not the cause. Proof of this is the sudden rise in abhorrence of Tequila among Americans reaching the age of 21 (21 being used loosely in this example).
Where correlations become trickier, and where we separate ourselves from the majority of our animal counterparts, is in inferring causation. Say when touching said switch you only occasionally get a shock, and you would like to continue using this switch. You would then need to figure out what is actually causing the shock. To do this, the natural response is to look for whatever factors are associated with being shocked. Say you get a shock only after getting out of the shower, you would immediately identify the most obvious difference between the two situations, and conclude that you cannot touch the switch while wet. To prove that having wet hands caused the shock, most people would dry them, then touch the switch again. However, it is also possible that being barefoot caused the shock. In the process of drying their hands, many people would put on clothes (I mean it would be silly to do an experiment naked, wouldn’t it?) and, completely unaware of the other factors that were changing, still conclude that wet hands caused the shock. And what if you only got shocked when you had both wet hands and were barefoot? In this case even drying your hands without putting on socks would lead you to falsely conclude that wet hands alone were the problem.
This is where I get on my metaphorical lab-bench and preach the value of science. Scientists are trained to perform an experiment in an absolutely controlled manner, before coming to a firm conclusion. An example of this is the necessary vs sufficient concept, something that is taught in all basic biology classes. To prove that wet hands are sufficient for a shock, you would take a situation where you got a positive result (a shock when wet) and only change one factor (being dry). To prove that wet hands are sufficient, you would take a situation where you got a negative result (no shock when dry and clothed) and only wet your hands. In this case, if bare-feet were also required, you would not get a shock, and would learn that you needed further experiments to fully understand why the switch hated you so much. This further experimentation, and never having the final answer, is also an inherent part (sadly) of the scientific process. In this case you would probably figure it out fairly quickly though, although adding each item of clothing individually might take a while.
Here is where some non-scientists will get on their soap-box (no bathroom pun intended) and say, who cares?! I don’t care if it’s bare feet or water, I don’t care that I might be slightly inaccurate if I say water causes a shock, as long as I don’t get a shock! I’ll stop touching the switch after the bath; I won’t get a shock, and everyone will be happy– and I will not stay up at night worrying if it was truly the water that was causing it. To this I say, absolutely true. But, what if you told all others to never touch the light while wet, and put out of work an entire group of wet light butlers (yes, the example reached it limits here, but undeterred and eager to make my point, I continued. Forgive me.)
All too often the habit of not properly attributing causation causes us to conclude something that negatively impacts the way we live our lives. And this is why, as a scientist, I truly value accurate experimentation before making conclusive statements of causation– and often irritate my non-scientist friends to no end when I analyze the causes of things they would much rather take for granted. But, as I talk about the fact that there is no conclusive evidence that vaccines cause autism, or that your blood type is linked to whether you should eat meat, or that cleansing your colon makes you lose fat, remember that in another place and time I could also be saying that that bump on your head doesn’t reveal your personality, or that leeches won’t purify your blood, or that drowning is not proof that one is truly a witch. Direct causation, although sometimes difficult to prove, is at least safe from the cultural logic of, say, the Spanish Inquisition.
And- for no reason other than the fact that I like how my new processing of this pic turned out, take a look.