/sci/ - Science & Math » Thread #11727842

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“Proof by contradiction”

Anonymous Thu 28 May 22:26:58 2020 No.11727842 View Reply Original Report

Quoted By: >>11727976 >>11728037 >>11728354 >>11728397

This must be true otherwise it would be so absurd!!

How is this still taken seriously?

Anonymous

Anonymous Thu 28 May 2020 23:01:39 No.11727976 Report

Quoted By:

>>11727842
What if it is absurd? What if reality involves inconsistent things? Reality might be more complex than our petty logical biases.

Anonymous

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Anonymous Thu 28 May 2020 23:02:46 No.11727983 Report

Quoted By: >>11728005 >>11728016 >>11728406

Imagine being underage

Anonymous

Anonymous Thu 28 May 2020 23:10:31 No.11728005 Report

Quoted By: >>11728360

>>11727983
Or, don't imagine not being underage

Anonymous

Anonymous Thu 28 May 2020 23:13:09 No.11728016 Report

Quoted By: >>11728117

>>11727983
Imagine using inferior indirect proofs to build up the foundations of mathematics.

Anonymous

Anonymous Thu 28 May 2020 23:17:16 No.11728037 Report

Quoted By: >>11728048

>>11727842
Depends on your truth semantics. In ordinary mathematics, it's a necessary evil for when you can't find a constructive solution or when an algorithm from the result isn't desirable.

Anonymous

Anonymous Thu 28 May 2020 23:20:26 No.11728048 Report

Quoted By:

>>11728037
It is a “necessary evil” and means that mathematics cannot be trusted because it is not solid.

Anonymous

Anonymous Thu 28 May 2020 23:42:44 No.11728117 Report

Quoted By:

>>11728016
Find superior ones then if you're so smart.

Anonymous

Anonymous Fri 29 May 2020 00:53:29 No.11728354 Report

Quoted By: >>11728372

>>11727842
What's hard to understand?
"Let's assume this thing is true. Blah blah blah, that implies 1 = 2 which is wrong. Therefore the thing can not be true".
Nothing wrong with this at all.

Anonymous

Anonymous Fri 29 May 2020 00:55:24 No.11728360 Report

Quoted By:

>>11728005
Based and underrated.

Anonymous

Anonymous Fri 29 May 2020 00:58:42 No.11728372 Report

Quoted By:

>>11728354
It requires that 1 need to be 1= 1. Ok but maybe it has only been so thus far. If we discover that 1=2 that could be an important anomaly to push us towards new discoveries. Instead we just say, uh, impossible we already know that 1=1. In short it privileges what we already think we know over what we are currently discovering. It is not an unshakable basis for truth.

Anonymous

Anonymous Fri 29 May 2020 01:05:19 No.11728397 Report

Quoted By: >>11728407

>>11727842
Suppose that OP is not a faggot.
Then this thread should be of high quality.
This thread is obviously not of high quality.
Hence OP is a faggot.
Shit thread kill yourself, son!

Anonymous

Anonymous Fri 29 May 2020 01:07:51 No.11728406 Report

Quoted By:

>>11727983
Good man

Anonymous

Anonymous Fri 29 May 2020 01:08:12 No.11728407 Report

Quoted By: >>11728418

>>11728397
Aha. But this is a great example to show why the proof is useless.

> Then this thread should be of high quality.
>This thread is obviously not of high quality.
Ergo you believe the contradiction means the opposite truth condition of the premise must be true, that OP is a faggot.

But
There could be a million reasons why this thread is obviously not of high quality.

Anonymous

Anonymous Fri 29 May 2020 01:11:18 No.11728418 Report

Quoted By: >>11728433

>>11728407
We may assume that if the thread is of low quality, then OP is a faggot necessarily.
You are right though, this proof is suited for a vacuum in which certain things always imply other things. So it doesn't always work in real life.

Anonymous

Anonymous Fri 29 May 2020 01:11:59 No.11728421 Report

Quoted By: >>11728424

In Ancient Greek thought, reductio ad absurdum was a rhetorical device to win arguments — not a dialectical device to provide true claims. Nobody has ever provided a serious reason why it is so rampant in modern math and science and logic.

Anonymous

Anonymous Fri 29 May 2020 01:12:47 No.11728424 Report

Quoted By: >>11728433

>>11728421
It works well for math and logic. Not necessarily science.

Anonymous

Anonymous Fri 29 May 2020 01:14:45 No.11728433 Report

Quoted By:

>>11728418
No because you would need to show that you’ve exhausted your possible premises and listed all of them. Then you’d need to introduce a single contradiction. >>11728424
It wins arguments and implies causality but it is not a direct proof. There is a reason why classical logicians only used is as a device of last resort. Today it’s the first thing anyone thinks of.

Assume the negation of the premise, this leads to contradiction, aha the premise must be true. That’s how math is done today.

Anonymous

Anonymous Fri 29 May 2020 01:16:19 No.11728438 Report

Quoted By:

Direct proofs generally work like this:

Assume this, now that follows, and this too, and wow this amazing result just follows.

Anonymous

Anonymous Fri 29 May 2020 01:18:15 No.11728442 Report

Quoted By:

If X were false it would be just so silly and so crazy that it must be true!

Anonymous

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Anonymous Fri 29 May 2020 01:55:12 No.11728544 Report

Quoted By:

Better version for shitposting purposes

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