... people have an unjustified tendency to assume that a person's actions depend on what "kind" of person that person is rather than on the social and environmental forces influencing the person. - Wikipedia, Fundamental Attribution Error

I would like to suggest that the fundamental attribution error relates, not only to the actions of individuals or groups (group attribution error), but also to their opinions, and knowledge.

Here’s a very simple example. I was told today that one should not put egg shells down a garbage disposal in the sink. I thought this was a ridiculous thought. I told the person who told me (who heard it from someone else, who heard it from someone else) that it was absolutely crazy.

I decided to do some research on the internet in order to find out who the crazy one really was. I discovered that I’m not crazy, but also that those who hold the egg shell theory as fact may not be so crazy either. And not because it’s true. I still don’t think it is.

Here’s a few things I found in very short research:

• Plumbers say not to put eggs down the disposal.
• Many plumbers also say not to put anything down at all.
• Water is OK to put down the drain. (whew!)
• People think ice and egg shells sharpen garbage disposal blades.
• Egg shells supposedly help clean a garbage disposal.
• Lots of pasta down a garbage disposal is not good.
• One guy said he's been to garbage disposal manufactures, installed/replaced many disposal units, etc. and that egg shells are not an issue.
• Too much of anything down the drain at once isn't good.

Some thoughts from all this:

1. People don't understand how sharpening a blade works. Basically, sharpening is the process of removing material from the blade in such a way that it leaves a thinner edge. The thinner the edge, the sharper the blade. You can also heat up the metal and shape it into a thinner edge. Ice in a disposal will not shave metal off the blades and it certainly doesn't heat it up. If either of these were the case you'd have little bits of metal shards in your homemade shakes and smoothies.
   
   
   
2. Plumbers have a skewed experience. I don't mean to suggest that their experience is wrong. Just skewed. Their experience (in my very limited knowledge of plumbers) is pretty much limited to two things: installing and fixing. When they install plumbing they don't have to deal with clogs. When they're fixing, there's a good chance it's a clog. A plumber can incorrectly assume that because many clogs have egg shells in them, you shouldn't put eggs down the drain. The reality is probably far closer to: don't put 4 cartons of egg shells down the drain at the same time. Or don't put down 12 eggs plus potato skins plus spaghetti. I'm guessing many hard boiled eggs at once wouldn't work out very well.
   
   
   
3. People's view of life is based on their experience and what they believe of the experiences of others. Trust your own biased experiences or the skewed/biased experiences of someone else and you'll only end up with more biased experiences. Trusting a plumber by not putting anything down the disposal probably won't be a big deal, but other things might.

I do realize I’m making a huge generalization about plumbers. I apologize, I don’t mean to skew anyone’s view of what a plumber does or thinks. I’m merely suggesting that making judgments off of the actions, opinions, and experiences of others, while valuable, should be used with caution. One should always get as much information as possible (from the right sources) before making a judgment call. Who said it? Where did they learn it? If it’s an action, is the person shy? Confident? Stressed? Perhaps their computer blew up yesterday and they lost all their family photos. You never know.