Deductive og inductive reasoning.

[Kindberg]

Wasn't sure if this would fit better into "Religion and Politics". But here I go.

I hear a lot that characters like Batman use deductive and Sherlock Holmes use inductive reasoning. So I tried finding out what that actually means. It mostly just led me to wikipedia.

I know there are deductive and inductive reasoning, are they the only to? What does it actually mean to have one of these reasoning, are one superior to the other? I didn't really understand the wikipedias example. Maybe someone in here wanna show his/her knowledge and explain it?

 

[Hungry Donner]

Inductive reasoning allows you to make assumptions and generalizations. For example Holmes may say, "this is an excellent quality hat but it is several years out of date and shows some wear, this suggests that the owner was wealthy but has fallen on hard times - he bought a nice hat and has been unable to replace it." However it could be that the owner was never wealthy and was given the hat as a gift and he can't replace it because he never had enough money for a hat like this, or maybe the owner is wealthy and he doesn't like newer styles, and doesn't mind that this one shows a little use.

Deductive reasoning only works with the facts you have:

1. Phil left the living room through the kitchen door.
2. Phil returned through the study.
3. The kitchen only has two doors (to the living room and study).
4. The study only has two doors (to the living room and kitchen).

We can therefore deduce that Phil walked from the living room to the kitchen, from the kitchen to the study, and from the study to the living room.

If we removed #4 we could only assume that Phil went from the living room to the kitchen and exited through the study (we know he didn't come back to the living room). However if the study has another door he could have left that way and done other things before coming back to the study and into the living room.

 

[Kindberg]

Thats pretty well explained, thanks! Bow for you sir.

 

[aba1]

I have to say that was a really clear explanation, nice!

 

[Hungry Donner]

Sherlock Holmes is a great way to explain inductive reasoning because he makes so many guesses and he generally explained them in depth. Sir Arthur Conan Doyle perhaps made him correct a bit too often, but then I suppose part of Holmes' appeal is that he's greater than human.

The hat bit is from the Adventure of the Blue Carbuncle. A man drops his hat (and cane?) and Holmes is able to draw a dozen conclusions about his life - which all turn out to be correct. But some of his conclusions are rather flimsy. There's also something about switching from candles to gas which is a bit better (the hat has wax stains of varying ages but none of them are recent).


I will throw out that mine is a very amateur opinion, if someone comes in with a stronger background in philosophy and logic I may be corrected on a few points.

 

[Nimcha]

Inductive reasoning allows you to make assumptions and generalizations. For example Holmes may say, "this is an excellent quality hat but it is several years out of date and shows some wear, this suggests that the owner was wealthy but has fallen on hard times - he bought a nice hat and has been unable to replace it." However it could be that the owner was never wealthy and was given the hat as a gift and he can't replace it because he never had enough money for a hat like this, or maybe the owner is wealthy and he doesn't like newer styles, and doesn't mind that this one shows a little use.

Deductive reasoning only works with the facts you have:

1. Phil left the living room through the kitchen door.
2. Phil returned through the study.
3. The kitchen only has two doors (to the living room and study).
4. The study only has two doors (to the living room and kitchen).

We can therefore deduce that Phil walked from the living room to the kitchen, from the kitchen to the study, and from the study to the living room.

If we removed #4 we could only assume that Phil went from the living room to the kitchen and exited through the study (we know he didn't come back to the living room). However if the study has another door he could have left that way and done other things before coming back to the study and into the living room.

Hah, I wanted to use a similar example. Thanks for saving me the trouble!

I also could point to the stock market, which is inherently unstable and completely unpredictable. This is because the traders almost exclusively use inductive reasoning to make decisions on what to buy and sell.