In simple words, what is the difference between 'possible' and 'probable'?

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6

Would anyone kindly explain the difference between these?

  • Possible

  • Probable

I have searched dictionaries and on all over the Internet, but I have not been able to understand yet what the difference is!

nima

Posted 2014-04-13T08:29:45.550

Reputation: 5 551

2what's the confusion? which definitions you got? What did you understand from them? – Maulik V – 2014-04-13T08:39:28.483

What is the difference between 'impossible' and 'improbable'? – Nico – 2014-04-13T08:41:23.653

I can not understand the difference between IMPROBABLE AND IMPOSSIBLE. Moreover, I can not understand the difference between POSSIBLE AND PROBABLE too. – nima – 2014-04-13T09:00:01.343

1Nice question! Your question is pretty deep also if we consider the technical meaning of probability and possibility. For example even if we define "probable" as "having probability bigger than 0", still probable != possible and improbable != impossible, because events that have probability 0 can be possible (e.g. guessing correct lottery number from a lottery that uses the whole natural number set). Possible/Impossible only related to the existence of such event, while probable/improbable can define the likelihood that the event. – Bakuriu – 2014-04-13T12:43:54.440

Answers

21

The specific percentage probabilities depend on context but in short;

  • Possible means it can happen, (be it unlikely or likely - however it is more often used for things which are unlikely)
  • Probably means it is likely to happen

Related terms;

  • Definite means it will happen.
  • Improbably means it could happen but it is unlikely
  • Impossible means it cannot happen

Use of probable or possible for things which are definite

It would feel very unnatural (and give the wrong meaning) to say that something definite was probable or possible and should be avoided. For example I would say "it is definite that I am using a computer to type this" not "it is probable I am using a computer to type this". This is because the strongest term should be used to describe the likelihood

However; when used as a condition it becomes acceptable. For example "If it is possible that it will be sunny tomorrow we will go to the park" or "If it is probable that it will be sunny tomorrow we will go to the park", if the weather reporter gives a forecast of 100% chance of sun then you still go to the park.

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Richard Tingle

Posted 2014-04-13T08:29:45.550

Reputation: 325

+1 I love the visualization here. Coupla minor thoughts: 1) The order seems semi-randoml I'd go from definite to impossible, with possible in the middle. 2) There seems to be an asymmetry at the extremes - I'd expect improbable and possible to touch the bottom in the same way possible and probably touch the top. (See what you get for giving us such a cool inch? Demands for feet!) – Jaydles – 2014-04-14T19:15:21.703

@Jaydles (1) completely agree, I'll fix that when I'm next on PC. (2) I let possible and probable touch the top (with a dashed background) because of what I was saying in my last paragraph. That arguably definately is a subcategory of possibly. I'm not really happy about that because its very context dependant. I'll have a think – Richard Tingle – 2014-04-14T21:47:05.267

I feel like I keep doing this on ell and English usage, but "It would feel very unnatural (and give the wrong meaning) to say that something definite was probable or possible and should be avoided" is yet another rule that is commonly broken ironically. So if we (especially in the UK) say, "it's possible that we have a tiny problem here", or "you probably don't want to do that", then we mean, "we have a serious problem", and "don't do that". So: you probably don't want to break the rule yourself until you get the hang of it, but possibly you should be receptive to others breaking it ;-) – Steve Jessop – 2014-04-15T00:18:13.447

14

In the NFL, injured players get listed week-to-week on an injury report, and each player gets of these statuses:

Probable: a 75% likelihood that the player will play
Questionable: a 50% likelihood that the player will play
Doubtful: a 25% likelihood that the player will play
Out: the player will not play

If an event is probable, there is better than a 50-50 chance that it will happen, although the word is usually reserved for something “comfortably above” a 50-50 chance. In other words, if I had 100 balls in a hat, and 52 of them were pink, and 48 of them were blue, I don't think I'd say, "I will reach in, and I will probably pull out a pink one." However, I might use probable if 67 balls were pink, and 33 were blue, and I'd be even more likely to say it if there were 90 pink balls and 10 blue ones).

The more likely an event will happen, the more suitable the word probable becomes.

On the other hand, possible means that there is a non-zero chance something will happen; it's used for a wider range of probabilities. For example, back to the bin with 90 pink balls, and 10 blue ones; I could say:

It's probable that I will pick a pink ball, although it's possible I will pick a blue one.

However, possible can be used even for probabilities over 50%. If a meterologist's weather model indicates a 60% chance of rain on Friday, a weather forecaster might say:

Temperatures will get cooler on Friday; rain is possible.

At some point (probably around 70% or so, although this is not something that is precisely defined), probable becomes a better word than possible. For example, if the weather model shows an 80% chance of rain, the forecaster might instead say:

Temperatures will get cooler on Friday; rain is likely.

(Likely and probable are synonyms in this context.)

Another way to look at it would be: All things that are probable are possible, but not all things that are possible are probable. Today, many things could happen to me: I could be attacked by a shark, struck by lightning, hit by a car, or take a walk. All of those are possible, but only one is probable.

J.R.

Posted 2014-04-13T08:29:45.550

Reputation: 108 123

Regarding the weather forecaster and probabilities, there is a joke: “What is the probability the weather you forecast to happen?” asked the reporter. “About 40%” answered the weather forecaster. “Why, then you don’t say vice versa”, replied the reporter. – Lucian Sava – 2014-04-14T06:22:59.973

1Regarding improbable and impossible: If the are 90 pink balls, and 10 blue balls, it is improbable that you will pick a blue one (and as such, probable that will pick a pink one). However, it is impossible that you would pick a green one, as that one isn't available for you to pick. – Tiberia – 2014-04-14T08:07:08.583

8

Probable means it's likely to happen. Possible means it could happen, but not necessarily likely.

Thinking Sites

Posted 2014-04-13T08:29:45.550

Reputation: 206

2This says it very nicely in a nutshell. – J.R. – 2014-04-14T10:01:17.850

5

Used on its own, "probable" means an event is very likely but not absolutely certain, without attaching a specific numerical probability. Similarly, "possible" means an event is not impossible, but says nothing about the numerical probability of the event being considered. Numerical probabilities can be used alongside the terms "probable" and "possible" but these will vary depending on the sort of risk being considered, and interpretation often depends on subjective judgements. In any case, once you specify numerical probabilities, the terms "probable" and "possible" really become redundant.

EG: "It is probable that a Cabinet Minister found guilty of unacceptable behaviour will resign in the following week, but anything is possible." "It is possible that it will be dry on any day in the year in London but it is probable that it will rain there on at least one day in October." "It is possible that you will be killed crossing the road in London but probable that you will reach the other side safely if you obey the signs and keep your wits about you."

Julian

Posted 2014-04-13T08:29:45.550

Reputation: 51

5

Possible: The probability of this happening is greater than zero. Antonym: impossible.

Probable: The probability of this happening is greater than 50%. Synonym: likely. Antonyms: improbable, unlikely.

It is possible that we will all be killed tomorrow by a solar flare, but it is extremely improbable.

keshlam

Posted 2014-04-13T08:29:45.550

Reputation: 229

2

When an event is probable, it is more likely to occur than if it were just possible. For example, it is possible that England will win the World Cup but it is probable that Brazil will.

KCH

Posted 2014-04-13T08:29:45.550

Reputation: 384

2I don't think this is a good example. Some people could argue that it is impossible that England will win the World Cup! (Nico runs away and hides) – Nico – 2014-04-13T12:32:05.910

5Haha! It impossible for Sweden to win the World Cup because they didn't qualify; but it is possible for England to win it because they have not been eliminated yet! Whatever you may think! – KCH – 2014-04-13T12:38:47.120

1Curse Gordon Banks's stomach ailment... – BobRodes – 2014-04-13T19:04:52.463

1p. s. If I may mention it, it is also possible that the US will win the World Cup. :) – BobRodes – 2014-04-13T19:07:45.057

Yes, correct, almost everything is possible. Yet few are probable, if any. – Lucian Sava – 2014-04-14T06:27:03.580

2

Possible means that an event can occur under the given circumstances.
Probable means that an event is likely to occur under the given circumstances.

If something is impossible, it is necessarily improbable. If an event cannot happen, it is unable to occur likely.

But a possible event can be not probable. Say you observe me eating eggs and you make a mental note. Then you might assume that it is very unlikely that I ever eat more than 3 eggs. You can watch for a lifetime and very probably my egg consumption will never exceed 3 eggs at a time.

But if you put a 1 kg gold ingot before me on the table and tell me: "Eat 10 eggs and you win this ingot", then you will see that it is possible for me to eat 10 eggs.

It is not probable that an nuclear power station will blow up under normal circustances. But it is entirely possible to blow up a nuclear power station if you or the systems screw up.

Thorsten S.

Posted 2014-04-13T08:29:45.550

Reputation: 21

1“No one can eat 50 eggs” :^) – J.R. – 2014-04-14T01:18:54.440

2

Possible - something can happen. Probable - something can happen, and there is a good chance of it happening.

However...

Impossible - something cannot happen. Improbable - something can happen, but there is a good chance of it not happening.

user1560834

Posted 2014-04-13T08:29:45.550

Reputation: 21

Great answer, thanks a lot – Gery – 2020-04-12T20:03:21.700

0

As you are Persian:

Possible = امکان دارد Probable = محتمل است

Possibility refers to the conditions required something happens.

Probability refers to likelihood, and Probable points to an almost high probability (likely)

It is possible that a woman bear five babies, though it is not probable.

Ahmad

Posted 2014-04-13T08:29:45.550

Reputation: 8 443

I can't say anything about Persian, but judging from your explanation, I think you misunderstood the two words. It's as other answers say, possible means it "can" happen, and probable means it's "likely" to happen. – Damkerng T. – 2015-08-02T08:11:31.463

@DamkerngT. Maybe my second example wasn't good as there were not much obvious difference, but in my first example and conclusion, I said the same you say, how not? The probability of son baby is almost 50%, but the possibility that a man bear a baby is zero (the condition is not provided) – Ahmad – 2015-08-02T08:23:03.093

1In my opinion, it's better to put aside logic, processes, and conditions to understand probable/possible, probably/possibly, and even probability/possibility (the noun pair is a little bit more complicated because there are more senses involved), and try to think in term of chance. If the chance is 0%, it's impossible. If the chance is not zero, it's still possible, no matter what. If the chance is high enough (like in the image in an answer here), it's probable. – Damkerng T. – 2015-08-02T08:32:08.097

@DamkerngT. Yeah you mean the degree of each, but we also can note to their basic meaning, as you also point possibility refers to "can", and probability refers to "likelihood", for example we discuss if it is possible that God exists or not (through logic), but if we talk about the probability that a baby is son or daughter (there is not much logic involved) – Ahmad – 2015-08-02T08:38:07.507

Try to focus on the adjective or adverb pair first. – Damkerng T. – 2015-08-02T08:40:05.940

@DamkerngT. You mean I could be right on the possible and probable as noun but the probably and possibly as adjective refers to the degree ? To me, it is probable that tomorrow is rainy is just a chance not how much (tomorrow have this chance), but probably, tomorrow is rainy means there is a high chance that tomorrow is rainy. about it is possible that tomorrow is rainy means almost high chance, as it implies we have observed some signs, though possibly tomorrow is rainy means a low chance – Ahmad – 2015-08-02T09:23:42.420

That's why I thought you mixed one of them up with the other. It looks like you still do. Both It is probable that tomorrow is rainy and Probably, tomorrow is rainy suggest that it's likely, not just possible. The same sentences with possible/possibly simply say that the chance is more than zero. – Damkerng T. – 2015-08-02T09:56:49.390

@DamkerngT. I feel you are right, I modified my answer, I feel I confused "It is probable" as "it is likely" with "there is a chance or probability for it" – Ahmad – 2015-08-02T12:15:46.993

-1

It's a matter of degrees that something will happen. Something that is possible is not necessarily probable, while something that is probable is more than possible. Probable would imply that something has more than 50% or higher of happening while Possible means that something could happen at varying degrees of certainty from 1% to 99% , because 0% would be absolutely not and 100% would be absolutely yes. So possible would mean 1% to 99% while probably would mean greater than 50% of happening.

user5744

Posted 2014-04-13T08:29:45.550

Reputation: 1

0% to 100% is the meaning of probability not possibility – Ahmad – 2015-08-02T08:57:41.893