Failures of Occam's Razor In Medicine

[lucaspa]

If you accept that The Priniciple of Parsimony is, of necessity, based on existing knowledge, then you will understand what I meant when I cited the example of the role of H.pylori in peptic ulcers.

 

When Warren and Marshall made their groundbreaking discovery, the following were the existing beliefs:

 

1. Ulcers are caused by an excess of acid or by a breakdown in the protective mechanism of the gastric mucosa, caused by a reduction in prostaglandin synthesis due to drugs such as NSAIDs.

 

2. Bacterial infection could have no role to play in this, as bactreria simply could not survive in the acid environment of the stomach.

 

3. Reduce the acid, and the ulcers would heal, and stay healed.

 

Now, statement 3 was implicitly based on statement 1. If you felt that acid caused ulcers, William stipulated that you followed that up by deducing that reducing acid would heal ulcers.

 

Agreed?

 

What do you claim is the "simpler" explanation? Remember, the Razor as (mis)used is not necessarily based on "existing beliefs" but on the "simplest" explanation. So in this case, which is "simpler" as a cause for ulcers: bacteria or excess stomach acid?

 

In order to make your argument work, you would have to say that bacteria causes the excess acid. In that case, then the "simplest" explanation is wrong.

 

We would have the statements:

1. "ulcers are caused by excess stomach acid"

2. "ulcers are caused by excess stomach acid due to the presence of aliens"

 

SkepticLance and Foodchain, compare #2 to the statement I posted about the motion of planets. In this case the "name" of the "aliens" is "helicobacter". BUT, by the formulation of the Razor you are using, we would accept #1 as being "most likely". Since that is the case, please answer this: why would we even bother exploring #2?

 

This is what I really hate about the misuse of the Razor: it stops scientific research and dismisses evidence out of hand! We don't have to look for helicobacter -- or ghosts -- because we have already made up our mind.

 

To get down and dirty, it's just what the creationists do when they say a literal Bible is correct. They start with a preconception and reject any data that doesn't fit. In SkepticLance's case, the preconception is that ghosts do not exist. That isn't based on "scripture", but just SkepticLance's prejudice. But now he applies the misused Razor to dismiss data that contradicts his prejudice. Just as creationists misapply scripture to dismiss data that contradicts their prejudice.

 

Remember my example of hypotheses about the origin of the universe? Since deity is the simplest explanation, isn't it "most likely to be correct"? So why don't you use the Razor in that case?

 

Anyway, let's move on. The purpose of this thread was not to have a philosophical discussion about the correct application of Occam's razor, but to inspire ourselves as a community, with tales of scientific breakthroughs that went completely against the perceived wisdom of that age. Discoveries so unintuitive, they were considered almost heretical at first.

 

Then you shouldn't have entitled the thread as you did or written the OP as you did! You should have titled the thread "Inspiring tales of scientific discovery" or some such.

 

Dhondy, what you are illustrating is what Karl Popper noted: science depends on imagination. Hypotheses are not simply digests of information. Instead, nearly always hypotheses/theories are leaps of imagination. Most often they are inspired by isolated pieces of data, but many times they are not. Instead the hypothesis/theory comes as a bolt out of the blue. The experiments come after the hypothesis and are designed specifically to test the hypothesis.

 

For anyone in science, your point is "DUH!" It's so obvious that we don't even comment on it among ourselves anymore.

[Dhondy]

OK, lucaspa, you have demonstrated that I know fack-all about Occam's razor.

 

Now can we have some more inspiring stories of breakthroughs in Medicine/science please?

[Dhondy]

Was reading an old article in NEJM, when I was reminded of Saint's triad. Saint exhorted us to look for three completely unrelated conditions in obese women presenting with abdominal pain- hiatus hernia, gallstones and diverticulosis.

 

Tummy pain in women in particular, and obese women, specially, can be caused by a combination of two or more of the above three conditions. If you follow Occam's razor, find pathology in one of the above, say the gallbladder, you risk missing out on the other two.

 

There is absolutely no correlation between the three, yet Saint's triad has stood the test of history.

 

Hickam, another physician, chipped in with, " A patient can have as many conditions as he bloody well likes."

[SkepticLance]

lucaspa

 

Your post of the 13th implies that you have not absorbed what I said earlier about probability.

 

Occams Razor is a tool. It is a useful tool when used correctly, just as applies to all tools. If applied incorrectly, it is misleading. It is used to decide which of various hypotheses is most likely, but does not remove the need to carry out the scientific process - that is, testing.

 

And yes. If you are superstitious and believe in ghosts, little green men from outer space, Loch Ness monsters, fairies at the bottom of the garden etc., then this principle proves terribly inconvenient.