Talk:Murphy's law

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Re: From the article "According to Richard Dawkins, so-called laws like Murphy's law and Sod's law are nonsense because they require inanimate objects to have desires of their own, or else to react according to one's own desires. Dawkins points out that a certain class of events may occur all the time, but are only noticed when they become a nuisance. He gives an example of aircraft noise pollution interfering with filming: there are always aircraft in the sky at any given time, but they are only taken note of when they cause a problem. This is a form of confirmation bias, whereby the investigator seeks out evidence to confirm their already-formed ideas, but does not look for evidence that contradicts them.[26]"

FFS the fact that Richard Dawkins grotesquely misunderstands this concept does not constitute any type of legitimate argument against it. Murphy's law does not represent on some type of anthropomorphism of inanimate objects or events. It rests purely on mathematics as I wrote about on this page earlier. Somebody should get Richard Dawkins to review how he has been quoted here and either repudiate the quotation or after some reflection admit that he weirdly misspoke himself.

Re: "Similarly, David Hand, emeritus professor of mathematics and senior research investigator at Imperial College London, points out that the law of truly large numbers should lead one to expect the kind of events predicted by Murphy's law to occur occasionally. Selection bias will ensure that those ones are remembered and the many times Murphy's law was not true are forgotten."

Murphy's law is a tautology. It is never not true by definition. It resolves to Any event with a probability of happening will happen. That's the very definition of an event that *must* happen as is alluded to by the reference to the law of large numbers. It is true that, for instance, a freak gamma ray knockout of a bit that catastrophically affects something is so exceedingly rare as to be reasonably (depending, though) dismissible. However, that is not what the application of Murphy's law is about. It is, at heart, either a warning that you will be disappointed if you allow something to go wrong because it will, or more importantly, in my opinion, an exhortation to review what *can* go wrong and deal with it so that it either can't go wrong or is dealt with appropriately when it does. Murphy's law, in practice, is a reminder to programmers to address edge and corner cases as well as things viewed as improbable in order to ensure either the failure is acceptable or that it has been dealt with. Selection bias and other biases exist, but so what in this instance? It does not affect Murphy's Law that people have a disproportionate recollection of when it was 'a thing'. It's still a reality whether people only remember it or don't remember it at all.

Re: "There have been persistent references to Murphy's law associating it with the laws of thermodynamics from early on (see the quotation from Anne Roe's book above).[22] In particular, Murphy's law is often cited as a form of the second law of thermodynamics (the law of entropy) because both are predicting a tendency to a more disorganized state.[28] Atanu Chatterjee investigated this idea by formally stating Murphy's law in mathematical terms and found that Murphy's law so stated could be disproved using the principle of least action.[29]"

How on earth could someone think that a tautology on its face can be 'disproved'. It is true by definition.

I do not see a serious academic both understanding Murphy's Law in its real world context and dismissing it as either untrue or unimportant. If you are a developer (this comes from software but in any endeavor), you ignore Murphy's Law at your peril. It will bite you. If you are an academic and attempting either to twist this into something it is not or somehow think that disproof of a tautology in this context is a meaningful thing, I despair for your academic institution.

Can somebody who is a neutral third party review and correct this offensively incorrect article on Murphy's Law? DeepNorth (talk) 00:04, 30 August 2024 (UTC)

Explanation with Probability

Edge Case Probability

• Consider an event with two edge cases: E₁ and E₂.
• Let P(E₁) and P(E₂) represent the probabilities of these edge cases occurring.
• Suppose P(E₁) = p and P(E₂) = q.

Corner Case Probability

• A corner case C occurs at the intersection of two or more conditions.
• If the corner case depends on both E₁ and E₂ happening simultaneously, then:

 $P(C)=P(E_{1}\cap E_{2})$

• Assuming E₁ and E₂ are independent:

 $P(C)=P(E_{1})\cdot P(E_{2})=p\cdot q$

Visualization and Interpretation

Probability of Edge Cases

• Let's assume $p=0.05$ (5% chance) and $q=0.05$ (5% chance).
• These probabilities might seem low, but they are significant enough to consider in testing.

Probability of Corner Case

• The probability of the corner case C occurring, given $p=0.05$ and $q=0.05$:

 $P(C)=p\cdot q=0.05\cdot 0.05=0.0025$

• This is 0.25% chance, much lower than the individual edge cases.

Murphy's Law Illustration

Murphy's Law states that if something can go wrong, it will. Applied to our scenario:

• Edge Cases: Each edge case has a 5% chance of occurring. These are already rare, but still within the realm of expected events.
• Corner Cases: The probability of a corner case is much lower (0.25%). Due to its rarity, it might be overlooked during testing.

Mathematical Picture

Imagine a grid where:

• The x-axis represents one condition (e.g., E₁).
• The y-axis represents another condition (e.g., E₂).

Each condition has a small probability of occurrence. The intersection (corner) where both conditions meet has an even smaller probability.

	Condition Not Met (¬E2)	Condition Met (E2)
Condition Not Met (¬E1)	Common Scenario	Edge Case (q)
Condition Met (E1)	Edge Case (p)	Corner Case (p \cdot q)

Summary

• Edge Cases: $P(E_{1})=0.05$, $P(E_{2})=0.05$
• Corner Case: $P(C)=0.0025$

Implication

• While edge cases are relatively rare, corner cases are even rarer.
• According to Murphy's Law, despite the low probabilities, over a large number of trials, even these rare corner cases will eventually occur.
• Because of their rarity, corner cases might not be adequately tested, leading to unexpected failures in real-world scenarios.

This illustration helps in understanding why it's crucial to consider both edge and corner cases during testing and why Murphy's Law suggests that these cases will inevitably manifest over time. DeepNorth (talk) 15:25, 12 June 2024 (UTC)

Murphy's law is NOT simply an adage

In the text I find:

- Murphy's law is simply an adage and is not grounded on logic or scientific laws.

That is not only incorrect, it is a profound misunderstanding of what the adage means in context and what necessary actions it implies. Software that does not account for edge cases and corner cases (that can go wrong) will inevitably fail (will go wrong). To the extent that you leave an avenue to failure in your software, whatever it may be, you have a defect that in the fullness of time *MUST* be encountered. This article does a disservice to starting and even journeyman programmers by incorrectly framing it as a sort of 'figure of speech'. It means they won't know what it really means in terms of implementation and importance. It also means, if this is their source of information, they won't even understand it or be able to explain it to anyone else. I am, in this regard, a primary source, so I won't change the article, but hopefully, if you are someone who always goes to the talk page (as I do, and as you should do), you will at least be aware that a professional production programmer with more than forty years experience learning the reality of Murphy's Law in practice has a different point of view and this additional explanation.

Murphy's law is true, deep, and somewhat subtle in its implications. It is a simple statement of tautological fact. By definition if it is something that *can* go wrong, it *must* go wrong eventually. — Preceding unsigned comment added by DeepNorth (talk • contribs) 15:25, 12 June 2024 (UTC)

This sentence was added last month by an editor saying that in my recent experience in social media, I've seen people take this seriously or believe that it comes from rigorous ground. I agree that it's incorrect to say that the adage is "not grounded on logic or scientific laws" when the article includes some framing of it as meaningful design advice. I'll take it back out. Belbury (talk) 15:51, 12 June 2024 (UTC)