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[NT] Deductive Logic: What Is It? Why Do We Do It?

Winds of Thor

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What effect(s) does using it have in life?

Do you benefit using it? If yes, why? If no, why not?

Does it seem geeky? Is it something some do but don't 'advertise'? :)
 

King sns

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of course we do, we use it all the time, it aids in our formation of reality all together. We have to make a lot of constant assumptions about the world and what we see to even stay sane and human. That's deductive logic in itself, no? It's VERY useful!
 

Winds of Thor

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of course we do, we use it all the time, it aids in our formation of reality all together. We have to make a lot of constant assumptions about the world and what we see to even stay sane and human. That's deductive logic in itself, no? It's VERY useful!

You're an NF. How does utilizing deductive logic combined with intuition benefit you?
 

Nicodemus

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of course we do, we use it all the time, it aids in our formation of reality all together. We have to make a lot of constant assumptions about the world and what we see to even stay sane and human.
Correct. It happens on all levels of (un)consciousness and is a natural part of how human minds work. Aristotle did not invent it.
 

Kalach

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Deductive: from truth to truth
Inductive: from evidence to explanation

Right?

So imma say "logic" is an ideal. You can fetishize it and speak of important and meaningful values and priorities, like (search for) TRUE and (shun the) FALSE. And probably these ideals do have their origin in people having cognitive "functions", though we should of course note that having cognitive "functions" is different from being ideal. Booyah!

But as for what is the meaning of logic after noting all that... I don't know.

(But with solipsism in the offing, we'd best believe, or try finding a way of proving, that our cognitive "functions", such as they are, probably do fairly literally partake of both the inner and outer worlds. These idealized values we as individuals and cultures build up and share around do reflect perfections of actual reality... somewhere.)
 

Mycroft

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As I understand it, inductive reasoning is, like Kalach says, looking at a body of evidence and forming an educated prediction. E.g., the sun has been observed to rise in the east and set in the west for fall of recorded history, so barring the existence of dynamics we are unaware of, we can reasonably infer that the sun will continue to rise in the east and set in the west.

Deductive reasoning, on the other hand, is when we can conclude something absolutely must be the case on the basis of its premises. For example, if we could somehow conclude that all swans were white and knew for certain that Steve the Swan was a swan, even without seeing Steve we could know he was white.

It seems to me we never really use deductive reasoning in our day-to-day lives, since everything we "know" we only know to degrees of certainty on the basis of evidence. All of our assumptions are best-fit explanations of the evidence.
 

Zarathustra

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Goddamit, I wrote a post about deductive, inductive and abductive reasoning, but lost it to the void.

Perhaps I'll write one up again.
 
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Why do you assume people do use it? A lot of people think they are being logical, but they're merely assuming whatever is left after skipping over important contradictions is true.
 

UniqueMixture

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Why do you assume people do use it? A lot of people think they are being logical, but they're merely assuming whatever is left after skipping over important contradictions is true.

Contradictions don't really exist. They're just opportunities for us to create a new heuristic that incorporates the new experience.
 

Winds of Thor

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Why do you assume people do use it? A lot of people think they are being logical, but they're merely assuming whatever is left after skipping over important contradictions is true.

This^ is so true. I used to talk to an INFJ when I was in school. She claimed was rational. Hehe.
She was a head case tho.
 

Little_Sticks

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Contradictions don't really exist. They're just opportunities for us to create a new heuristic that incorporates the new experience.

I've wondered something similar. Contradictions only really become contradictions once they are found; previous thought has no contradiction until it is presented with one.

In this sense, there are intellectuals that go looking for contradictions, where unsatisfied, each solution to a problem becomes its own problem, and those that are satisfied when a solution is found, accepting any flaws as a natural order to life.

The former is a bit more comforting to those that seek to be less ignorant, but its inaction leads to its own kind of ignorance. The latter is a bit more comforting to those that appreciate how inaction produces nothing of its own accord, but its action dons an implicit ignorance.

Which one is the lesser of the two evils?
 

onemoretime

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As I understand it, inductive reasoning is, like Kalach says, looking at a body of evidence and forming an educated prediction. E.g., the sun has been observed to rise in the east and set in the west for fall of recorded history, so barring the existence of dynamics we are unaware of, we can reasonably infer that the sun will continue to rise in the east and set in the west.

Deductive reasoning, on the other hand, is when we can conclude something absolutely must be the case on the basis of its premises. For example, if we could somehow conclude that all swans were white and knew for certain that Steve the Swan was a swan, even without seeing Steve we could know he was white.

It seems to me we never really use deductive reasoning in our day-to-day lives, since everything we "know" we only know to degrees of certainty on the basis of evidence. All of our assumptions are best-fit explanations of the evidence.

It's interesting, though, because the nature of deductive reasoning is quite different among various disciplines. In mathematics and philosophy, deductive reasoning is essentially probative, given their high levels of abstraction. Meanwhile, in the hard sciences, deductive reasoning leads to hypotheses at best, while still demanding empirical observation of the concluded phenomenon. In the soft sciences, deductive reasoning is more a means of argumentation than proof, as it is likely that there will be few premises that all will agree upon as factual.
 

UniqueMixture

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I've wondered something similar. Contradictions only really become contradictions once they are found; previous thought has no contradiction until it is presented with one.

In this sense, there are intellectuals that go looking for contradictions, where unsatisfied, each solution to a problem becomes its own problem, and those that are satisfied when a solution is found, accepting any flaws as a natural order to life.

The former is a bit more comforting to those that seek to be less ignorant, but its inaction leads to its own kind of ignorance. The latter is a bit more comforting to those that appreciate how inaction produces nothing of its own accord, but its action dons an implicit ignorance.

Which one is the lesser of the two evils?

I was presenting this not as a fundamental truth, but rather as a useful tool :)

If you do not state it in absolutist terms, it does not have the same emotional impact.
 

Mycroft

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It's interesting, though, because the nature of deductive reasoning is quite different among various disciplines. In mathematics and philosophy, deductive reasoning is essentially probative, given their high levels of abstraction. Meanwhile, in the hard sciences, deductive reasoning leads to hypotheses at best, while still demanding empirical observation of the concluded phenomenon. In the soft sciences, deductive reasoning is more a means of argumentation than proof, as it is likely that there will be few premises that all will agree upon as factual.

I'm interested in knowing a lot more about mathematics than I currently do. It's a thing of interest to me, how on one hand mathematical systems can be internally consistent but totally divorced from reality, yet on the other hand make predictions that are internally consistent and seemingly divorced from reality (or which at least fly in the face of common sense), but which are eventually supported by evidence.
 

redacted

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Contradictions don't really exist. They're just opportunities for us to create a new heuristic that incorporates the new experience.

Contradictions do exist, it's just that the premises can't be true.

But I guess that's what you're saying -- that when we see a contradiction, it forces us to change our assumptions.
 

UniqueMixture

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[MENTION=1654]Evan[/MENTION] yeah, though I admit the number of mathematicians who believe that proof by negation is not true is fairly tiny (probably less than 1%). In my view it is not necessary so I find it awkward to use because it makes my conclusions feel more tenuous. Also, I believe there are real psychological/emotional benefits to NOT :) D lol) believing in it.
 

Qlip

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I'm a computer programmer, I use inductive reasoning on a daily basis, and I'm quite familiar with the pitfalls and possible errors when employing it. Even when working within a system that you yourself created, the different variables involved can become increasingly complex beyond your ability to be certain about all of its properties. But, even so, inductive reasoning is sometimes the only tool for the job. Of course, in my specific applications I can empirically test to see how often I am right or wrong. Some people don't have that type of familiarity with the hits and misses of their own reasoning processes.
 
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