TIL: Today I Learned

[SS-18 ICBM]

There are a number of differences between the International Court of Justice (ICJ) and the International Criminal Court (ICC). In short: the ICJ is older and directly connected to the UN. It adjudicates disputes between governments, as opposed to individuals. The subjects of ICJ disputes are typically more related to civil law (e.g. trade, boundaries) as opposed to criminal law (e.g. genocide).

 

[Live trash can]

Induction and Deduction

An example of induction: You study a range of different religions and from these studies make a theory which concludes that all religions have a certain characteristic.

An example of deduction: You have a theory and conclude that a certain religion has the characteristic that you find in your theory. For example that Islam includes belief in spiritual beeings.

If this is wrong, please tell me!

 

[sophie]

Inductive Reasoning: Judaism has one God. Christianity has one God. Islam has one God. Therefore all Abrahamic Religions must be monotheistic
Deductive Reasoning: If all Abrahamic religions are monotheistic, and Judaism is an Abrahamic religion, then Judaism must be monotheistic.

Another example:

Inductive Reasoning: Dave is wearing a coat, Jim is wearing a coat, Alex is wearing a coat. Therefore, when I meet my friend Nick later today, he will be wearing a coat.
Deductive Reasoning: People wear coats when it is cold. Chicago is cold right now. Nick is a person. Therefore, Nick will be wearing a coat when I see him.

Inductive Reasoning is a conclusion you came to through observed patterns. Inductive reasoning is open to the possibility of being wrong assuming new data contradict the pattern that has been observed. Deductive Reasoning is a conclusion you came to through logical principles (most commonly syllogisms) and assumptions. Conclusions based on deductive reasoning will never be incorrect so long as the logic is sound and the assumptions you are making are correct. Think about geometric proofs that you might have done in high school: those are based purely on deductive reasoning - we know that the angle of this triangle is proportional to the angle of this triangle because of a number of postulates and mathematical principles that we can point to (i.e. proven assumptions), as opposed to an inductively reasoned proof where we'd have to look at dozens of triangles and measure the angle of each to come to a conclusion about what the angle we're trying to find would be.

 

[Live trash can]

Isn't the problem with deductive reasoning, apart from syllogisms, that we lack conclusive evidence of the theory? Even if we find many cases where the theory is right, we could in the future find an example where the theory doesn't hold.

 

[sophie]

Isn't the problem with deductive reasoning, apart from syllogisms, that we lack conclusive evidence of the theory? Even if we find many cases where the theory is right, we could in the future find an example where the theory doesn't hold.

The whole point of deductive reasoning is that you don't need examples. A deductively reasoned argument will always be correct so long as the assumptions it rests on are correct and the logic it employs is correct. This is why math regularly uses deductive reasoning.

 

[Live trash can]

The whole point of deductive reasoning is that you don't need examples. A deductively reasoned argument will always be correct so long as the assumptions it rests on are correct and the logic it employs is correct.

I think it is different in maths from other areas. If for example you say that "all birds can fly", this will seem correct, until you enconter a penguin or an austrich.
A deductive theory is like a working theory or a theory in progress.
And for most of our purposes it will be solid if the reasoning is solid.

 

[sophie]

I think it is different in maths from other areas. If for example you say that "all birds can fly", this will seem correct, until you enconter a penguin or an austrich.
A deductive theory is like a working theory or a theory in progress.
And for most of our purposes it will be solid if the reasoning is solid.

That's not deductive reasoning though. That's a declarative statement. A deductively reasoned argument would be: "If all birds can fly, and ostriches cannot fly, then an ostrich must not be a bird." Now this is an untrue statement. An ostrich is a bird. However, there is nothing about the logic that is invalid, given that the assumptions are correct. What is invalid is the assumption that "all birds can fly". However, you could change the assumption to: "All birds have feathers. Ostriches have feathers. Therefore, an ostrich is a bird". And it works. Or you could make it more complex than that: "All birds have beaks (A). All birds have feathers (B). All birds lay hard-shelled eggs (C). All birds have wings (D). A penguin has A, B, C, and D, therefore a penguin must be a bird. An ostrich has A, B, C, and D, therefore an ostrich is a bird. A T.Rex has C, but not A, B, or D, therefore a T.Rex is not a bird."

 

[Live trash can]

I know there is something called something like the Hypotetico-Deductive Method. I think what I described is at least related to that. Something about testing our hypothethis in the real world.
But I don't completely get it!
Logic is not of my favourite things though, so I don't mind

 

[Lemon Merchant]

Induction and Deduction

An example of induction: You study a range of different religions and from these studies make a theory which concludes that all religions have a certain characteristic.

An example of deduction: You have a theory and conclude that a certain religion has the characteristic that you find in your theory. For example that Islam includes belief in spiritual beeings.

If this is wrong, please tell me!

Both are deductions.

Owen explained it better.

 

[Live trash can]

I'm not sure I understand them. But I probably use both without knowing it.

That's the beauty of Logic.

 

[Mouthwash]

However, you could change the assumption to: "All birds have feathers. Ostriches have feathers. Therefore, an ostrich is a bird". And it works.

No, it doesn't.

 

[Timsup2nothin]

No, it doesn't.

Yes, it does. The assumption is still open to challenge, but the logic holds.

Spoiler :

Actually, it doesn't, because the assumption that is needed for it to hold is "all feathers are found on birds", rather than "all birds have feathers." However, a rebuttal to the arrogantly unsupported statement from Mr Rinse and Spit was called for.

 

[Mouthwash]

So I'm wrong, but I'm right? Sounds like you have your own logical issue there.

 

[Arakhor]

Anyone can say, "no it doesn't" and learn absolutely nothing from the process. Just pooh-poohing something because you disagree is meaningless unless you know why.

 

[Mouthwash]

It's a very classic error. I assumed that once their attention is drawn to the fact that it's wrong, most people could figure out why.

 

[Arakhor]

You didn't seem to know why and if you did, it would have behoved you to point out why.

 

[Mouthwash]

I'd like to think my reputation isn't such that people assume I call others mistaken for no reason.

 

[hobbsyoyo]

We all come here to read each other's thoughts and reasoning. 3 word responses can all to often be read as intentional jerkishness.

 

[Synobun]

Simply replying with "nah" is the height of intellectual dialogue.

 

[hobbsyoyo]

Whatevs