Wednesday, February 03, 2010

Deductive versus Inductive Reasoning

Today at the Adams School we had a lesson in deductive versus inductive reasoning and why a second opinion is a good thing.

A little background information for you. As part of our home renovations a few years ago, we put all new plumbing in the house, but we did not do anything to the main line coming into the house. This was for two reasons, you can see that the pipe coming into the house is copper and when we bought the house there was an indentation in the yard leading to the water line, so we figured it had all been replaced not that long before.

Besides not messing with the main line, we also left a weird, very, very old hose connection in the flower bed by the house that is attached directly to the main line before the shut off for the house. Every time we have a deep freeze and rapid warm up, the pressure fitting in that pipe blows and spews water all over everything. You have to shut the water off at the street to put it back together, and it takes a very strong person lying flat on their stomach to turn it off. I can't do it even when I'm not pregnant.

I've had to call Justin and get him to come home from work to shut this spewing pipe off more than once (good thing we live close to his office). So we finally got tired of this and called a plumber out to talk about fixing it several weeks ago.

The first plumber came out dug around a little, told me he couldn't put his threading machine on the old pipe, because it would snap. He never dug down to the main line, but informed me that it had to be galvanized pipe because a good plumber would never stick galvanized pipe into copper pipe. Nor would they reattach old pipe to new. He told me that we'd probably need to replace the entire thirty feet of pipe from the street to the house -- all without taking a look at the pipe underground.

This my friends, is DEDUCTIVE REASONING. Take a set of assumptions -- starting with the idea of what only "good" plumbers would do, for instance, and working from there to a conclusion without investigating the facts.

Today, the plumbing company sent out a different plumber. He said he'd seen all sorts of odd things done to old houses and pipes and before he unloaded the big digging machine he decided to actually check what was down there with a shovel. In other words, he went looking for facts on which to base his conclusions. INDUCTIVE REASONING.

Maybe no good plumber would have stuck an old galvanized hose pipe into a copper pipe, but that's exactly what was done at our house. At some point a new main line had been run from the street, as we'd always believed. There is nice new pipe all the way along. But when those plumbers, before we bought the house, ran the line they kept the ancient galvanized hose pipe and fitted it into the new copper pipe.

Pulling out the crummy pipe and capping it cost almost exactly $1000 less than running a whole new line. If the first plumber hadn't been lazy and not wanted to dig the first day, we would have gotten it fixed weeks ago when we first called them. I haven't yet decided whether the first plumber was trying to up his amount billed this month or not.

And of course, if we had done the digging ourselves ages ago, we would have known what the problem was and could have gotten a cheaper plumber to come out after hours and fix it for far less. Still, I practically feel rich without the giant bill I thought was headed our way.

Remember folks, the more facts you have the better position you will be in to figure out a solution. Faulty logic sets you up for a mess.

1 comment:

Herb of Grace said...

My hubby would love this post :) He teaches logic to middle schoolers. I know. A thankless job. But someone's got to do it! ;)

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