Possibility vs. Probability – Which is Correct?

While both possibility and probability are correct and widely used in English, they denote distinct levels of likelihood. Possibility refers to something that can happen, regardless of how likely, indicating a non-zero chance. Probability quantifies the likelihood of an event occurring, expressed as a numerical value between 0 and 1, or as a percentage.

Possibility or Probability – Which is Correct?

Both possibility and probability are grammatically correct and valid words in American English, but they are not interchangeable. The core difference lies in the degree of certainty and measurability they convey. Possibility simply means that an event is not impossible; it could potentially happen. It’s a binary concept: either something is possible or it isn’t. Probability, on the other hand, assigns a numerical value to how likely an event is to occur, often based on data, statistics, or logical reasoning. It’s a spectrum, ranging from 0 (impossible) to 1 (certainty).

The Best Trick to Remember the Difference

A powerful trick to remember the difference is to think about measurement. If you can assign a number or a percentage to how likely something is, you’re dealing with probability. If you can only say “yes, it could happen” or “no, it couldn’t,” you’re dealing with possibility. Think of possibility as a gate – it’s either open or closed. Think of probability as a dial that measures how wide the gate is open, from fully shut (0%) to fully open (100%).

Word	Part of Speech	Meaning	Example
Possibility	Noun	The state or fact of being possible; a chance that something may happen or be true.	There’s a possibility of rain tomorrow, even if it’s a small chance.
Probability	Noun	The extent to which an event is likely to occur, measured by the ratio of the favorable cases to the whole number of cases possible.	The probability of rolling a six on a fair die is 1/6.

How to Use Possibility

Possibility refers to the simple fact that something is not impossible; it exists within the realm of what could happen. It doesn’t imply any specific likelihood, only that the event is conceivable or achievable. It’s often used when an outcome is uncertain but not ruled out, or when discussing potential options or scenarios. The tone is generally neutral, simply stating that an event is on the table.

Example 1: There’s a possibility that we might finish the project ahead of schedule, but it’s not guaranteed.

Example 2: She considered every possibility before making her final decision, no matter how remote.

Example 3: Is there any possibility of rescheduling our meeting for next week?

What are the different forms of Possibility?

Possibility is a noun. Its primary form is singular, and its plural form is used when referring to multiple potential events or outcomes.

• Singular: possibility
• Plural: possibilities

Etymology of the word Possibility

The word “possibility” comes from the Old French possibilite, which itself is derived from the Latin possibilitas, meaning “power, capability, possibility.” This traces back to possibilis (“that can be done, possible”), from posse (“to be able”). Its roots emphasize the core meaning of “being able to be.”

How to Use Probability

Probability is a quantitative measure of how likely an event is to occur. It moves beyond a simple “yes/no” and assigns a numerical value, typically between 0 (impossible) and 1 (certain), or as a percentage (0% to 100%). This word is crucial in fields like statistics, science, economics, and risk assessment, where precise forecasting is necessary. When using probability, you are often discussing calculated chances, informed predictions, or statistical likelihoods.

Example 1: The meteorologist stated that the probability of snow is 70% for tonight.

Example 2: Based on historical data, the probability of a system failure within five years is quite low.

Example 3: Winning the lottery has an extremely small probability, but it’s still possible.

What are the different forms of Probability?

Probability is a noun. Its primary form is singular, and its plural form is used when referring to multiple statistical likelihoods or calculations.

• Singular: probability
• Plural: probabilities

Etymology of the word Probability

The word “probability” originates from the Latin probabilitas, meaning “credibility, likelihood, probability.” This stems from probabilis (“credible, believable”), which comes from probare (“to test, prove”). The etymology highlights the idea of something being “provable” or “testable” to determine its likelihood.

Related Concepts

Understanding broader concepts like certainty and chance helps to further clarify the distinction between possibility and probability.

• Certainty: This refers to an event that is guaranteed to happen (100% probability) or guaranteed not to happen (0% probability). It’s the extreme end of the probability spectrum, beyond mere possibility.
• Likelihood: Often used interchangeably with probability in casual speech, likelihood generally refers to the chance of something happening. While probability quantifies this chance precisely, likelihood can be more qualitative (“high likelihood,” “low likelihood”).

Examples from Media and Literature

• “The possibility of success, however remote, was enough to motivate them.” – From a business news report discussing a startup venture.
• “In the vastness of space, the possibility of alien life forms seems almost inevitable.” – A quote from a science documentary.
• “The probability of a coin landing on heads is 0.5, assuming it’s a fair coin.” – From a textbook on introductory statistics.
• “There was a high probability that the suspect would attempt to flee, so officers were on high alert.” – From a crime novel.
• “Every decision opens up new possibilities and alters the probability of future events.” – A philosophical reflection in an essay.

Practice Exercises

Choose the correct word to complete the sentence.

1. Given the current weather patterns, there’s a strong ______ of rain this afternoon.
2. Even if it’s unlikely, there’s always a ______ that your forgotten keys are still in your pocket.
3. The company calculated the ______ of a market downturn to inform their investment strategy.
4. With enough effort, any goal, no matter how ambitious, holds the ______ of achievement.
5. What is the ______ of rolling a number greater than four on a single six-sided die?

Answer Key

1. probability
2. possibility
3. probability
4. possibility
5. probability

Possibility Synonyms

Synonym	Definition
Chance	A likelihood of something happening; an opportunity.
Potential	Latent qualities or abilities that may be developed and lead to future success or usefulness.
Feasibility	The state or degree of being easily or conveniently done.

Probability Synonyms

Synonym	Definition
Likelihood	The state or fact of something being likely to happen; probability.
Odds	The chances or likelihood of something happening or being the case.
Chance	A possibility of something happening; a measure of how likely something is.

Frequently Asked Questions

Question 1: Can something be possible but have a zero probability?
No, by definition, if something has a zero probability, it is impossible. If something is possible, it means there is at least some non-zero chance, however small, of it occurring.

Question 2: Is “chance” a synonym for both possibility and probability?
Yes, “chance” can be used in both contexts. It can refer to a mere possibility (“there’s a chance it might rain”) or a quantified probability (“a 50% chance of rain”). The specific meaning often depends on the context and whether a numerical value is implied.

Question 3: In what fields is the distinction between possibility and probability most critical?
The distinction is crucial in fields requiring precise risk assessment and forecasting, such as finance, insurance, scientific research, engineering, and statistics. In these areas, knowing if something is merely possible versus knowing its exact probability can have significant practical implications.

Conclusion

Mastering the distinction between possibility and probability enhances the precision and clarity of your communication. While possibility opens the door to what can be, probability quantifies how likely it is to walk through that door. Understanding this nuance allows you to convey not just whether an event is conceivable, but also its measurable likelihood. Pro Tip: Using these terms correctly reflects a sophisticated understanding of language and logic, bolstering your professional reputation and analytical skills.