Cfrtjryk

There are some good answers here. I thought it would be useful to expand on meaning (5) in your list, in case you ever have to deal with it.

In English common law, most matters (criminal or civil) came to be tried by a jury. Over time a rule developed that some questions would be decided by the jury and others by the judge. The jury decided questions of fact whereas the judge decided questions of law.

For example, in the English law of theft, one element of the crime that must be established by the prosecution is that the defendant acted "dishonestly". The meaning of "dishonest" is a question of law, but whether the defendant was dishonest according to that definition is a question of fact.

There are practical consequences of this distinction. In English criminal procedure, you may appeal the judge's decision on questions of law, but not the jury's decision on questions of fact.

In this usage "fact" is used in a slightly technical sense in opposition to the word "law" but it is essentially intended to be restricted to statements that are true, at least that is the hope.

Your question sounds as if you are in a Quixotic fight against a particular false Scotsman, not realising that there is no such thing as a true Scotsman, or for that matter, a true X for any word X whatsoever.

You could just as well be "struggling to decide whether to jettison use of the word word, because the definition appears to be not solid enough to support continued usage". There is no clear boundary between what is a word and what isn't. Is "ouch" a word? Or "hmmm"? How about "Aargh"? "Aaaaaaaaaaaaaaaaargh"? Is "blasé" an English word? What about "révisioniste"? Is "Agatha"? And "Christie"? Is the symbol used by 'the artist formerly known as Prince' a word? Is "a priori" an English word? Or is it two? How about the two constituents? Note also that in languages which do not separate words by spaces, it can be practically impossible to distinguish separate little function words from suffixes or prefixes.

Who is this I who is struggling anyway? Do you mean your body, your mind (whatever that is) or your soul (whatever that is)? Did this I already exist when 'you' were born and possessed only a tiny percentage of the atoms that you would now consider your own, whereas many of the atoms 'you' possessed then have found something else to do in the meantime? Did it already exist before you could think clearly and create memories that you can still draw on?

What do you mean by struggle to decide? Who is this ominous person trying to prevent you from deciding, the one you apparently have to struggle against?

What do you mean by the definition? Since when do words have unique, well defined definitions? Where would you be able to find the one true definition of a word? How would you be able to understand it without using similar definitions for all the words used in it, leading to loops and an infinite regress?

Facts are true because (in some sense that I don't wish to make precise) the meaning cloud for the word fact is mostly a subset of the meaning cloud for the word true. Although false facts are mostly outside the one for true, while still in the periphery of the one for fact.

For similar reasons, birds can fly even though some birds have broken wings or happen to be penguins. And facts are true even though some are not.

Does a “fact” have to be true?

No.

Here is a detailed definition of fact from OED for the sense that we are dealing with:

A thing that has really occurred or is actually the case; a thing certainly known to be a real occurrence or to represent the truth. Hence: a particular truth known by actual observation or authentic testimony, as opposed to an inference, a conjecture, or a fiction; a datum of experience, as distinguished from the conclusions that may be based on it.

But it is also mentioned that:

Where the truth of a matter is disputed or in doubt, this sense overlaps with sense "A piece of information allegedly or conceivably true; something presented as a fact but which is disputed or unproven; (more strongly) an unproved assertion, an allegation."

In fact, the truth is, it depends.

You understand that the fact is not a truth from the context. Usually, the negative words like false, unproven, disputed etc. reveal that. (They might modify fact also.)

Some examples from OED:

• This is..a false fact, supported by a supposed motive - 1824, Westm. Rev.
  



• It bases its accusations on false statements and inaccurate facts. - 1941, A. M. Lindbergh Diary




• Waksal hotly disputed some of the facts in that story. - 2002, Vanity Fair

_{Note: Of course it can be discussed or interpreted further but I focused on the usage of the word.}

I think that you are reading too much into the last two definitions listed. The fifth one is apparently a legal term of art and as we all know lawyers have little use for the actual truth. The fourth covers instances where facts are asserted without being verified. If I asked a group of toddlers for a list of facts about where babies come from, that's still a list of facts.

Finally, the same argument can be made for truth, "a fact or belief that is accepted as true" being one of its meanings. So now we're trespassing into the realm of epistemology.stackexchange.com.

"What I'm really after... is whether the adulteration of this particular word renders it...meaningless, and therefore something to be avoided."

The word is not being "adulterated"; it is being used in different ways in different speech contexts.

A fact is that which exists or existed, happens or happened, and which can, as a result, be *known, thought, supposed, believed, stated, averred, alleged, etc".

These ancillary definitions involving speech contexts are not really definitions of "fact" per se but of the kinds of mental attitudes we can express, or the kinds of predications we can make, in respect to ontological fact. The lexicographers have made a leap from ontology to (everyday) epistemology.

When I refer to something as a fact, without qualifications, I am implying that it is true. This situation is not much different than when I say something like "I ate a grapefruit for breakfast." I am implying that I actually did. I might be lying, but the meaning of my sentence is that my eating of a grapefruit is the truth. I can refer to an event as alleged, no longer implying it is necessarily true: "Allegedly, he ate a grapefruit for breakfast." Similarly, I can use the word fact to refer to that event, whether true or not: "The alleged fact of your eating a grapefruit is immaterial to the question at hand." It is possible to drop the word alleged in this last sentence, and without it, the sentence will be ambiguous about whether I am implying that you did eat a grapefruit. Some people will interpret it to mean I implied you did, others will interpret it to mean I am agnostic.

As the definitions you quote indicate, the word "fact" is used in two different senses. It can mean something that is true, or it can mean something that is claimed to be true, but which may or may not actually be true.

On the one hand, people will say things like, "It is a fact that Senator Jones accepted a bribe." Meaning, this statement is true. Or conversely, "No, that's not a fact at all." Meaning, that statement is false.

On the other hand, people also commonly say things like, "The facts are in dispute", meaning, we are arguing about what is true and what is not. Editors talk about "fact-checking" a document to determine whether the facts it states are true or not. We talk about "unproven facts" or "questionable facts". We say, "You have your facts wrong." Etc. If the word "fact" was understood to mean "statements that are true", then it would be a paradox to say "unproven facts" or "disputed facts" or "the facts are wrong". How can something that we all know is true be in dispute, etc?

From Hard Facts: nuances in meaning and usage exist, but there are good reasons to use both terms:

• What is the clear difference between a fact and a truth? Well, if you look into most dictionaries, you will be amazed to find that the two words are actually very close in terms of their definitions. This is because the two terms are very much related. That’s why you really can’t blame people for recognizing both as similar terms.




• Fact is basically something that exists, or is present in reality. Hence, these are things that can be seen visually, and these are the things that can actually be verified. Facts are objective matters rather than subjective ones. It is not just something that you believe, but rather these are more or less the things that can be observed empirically, or by the senses. So, facts can be seen and heard, as well as proven by the other senses.




• Truth can be described as the true state of a certain matter, may it be a person, a place, a thing or an event. It is what a person has come to believe. If he believes that something is true, then it is true. It also answers the questions of what’s really happening. In the technical sense, facts can answer certain ‘why’ questions, like ‘where’ or ‘when’, and even ‘how’, while truth answers the question ‘why’. The question of ‘how’, and even ‘what’, are said to be answerable by either of the two.



• 
  

  In terms of permanence, a fact happens to be more permanent, and almost always seems to have no changes. It is more constant than truths. For example, when you say that the sun will always rise from the east and set in the west, you are telling a fact, but when you say that you are in Los Angeles, then that is a truth, at least for that exact moment. Several hours from that time you may have gone somewhere else, making your previous statement a fallacy. Thus, a truth is something that is not universal, it is more subjective, and depends on the current situation. That’s why the truth’s existence is said to be more temporary than that of facts.

  
  
  
  
  
  1. Facts are more objective when compared to the more subjective truths.
  
  
  2. Facts are more permanent when compared to the more temporary truths.
  
  
  3. Facts exist in reality, whereas truths are usually the things that one believes to be true, or the things that are true in the current situation.
  
  
  4. Facts can also answer the ‘where,’ ‘when’ and ‘how’ questions, whereas truths answer the ‘why’ question.
  
  
  
  

There are basically two types of facts: Universals, which are universally true and is usually part of common sense about how the physical world works, and Facts that are statements you believe are true, but not necessarily.

In your precise case, about the usage of the word "fact" for communication purpose, we must also account for the incompleteness and incertainty of the interlocuter: he/she may be using a prejudice that is just false, or be lying, or just misestimating his/her level of confidence in the statement he/she made.

So, in the end, a fact can only be what one believe is true, as opposed to what is true universally.

BTW, this is a very important topic of research in knowledge representation, logics, artificial intelligence and in any ontological system (ie, systems that represent knowledge) in general.

Yes, a fact has to be true -- in a verifiable sense, unlike an opinion.

NOAD gives this listing:

fact |fakt|
noun
a thing that is indisputably the case : she lacks political experience—a fact that becomes clear when she appears in public | a body of fact.

A belief is not "indisputable", so a belief, without any other evidential backing, by definition, cannot be a fact.

There may be some cases where something previously considered fact has become untrue, due to the evidence available at the time being superseded by newer evidence, but in all cases it would be correct to say:

"A fact is a statement which currently available knowledge and evidence supports to be true."

It would be very bad to state:

"A fact is something believed to be true", as this can easily imply that all beliefs are as good as hard evidence. Without evidence, a "fact" is just an opinion.

I'm not really looking for a discussion of truth in the philosophical sense. The scope of this question is limited to the meaning of a word in English, not the meaning of an absolute concept as rational beings can or should understand it.

I'm afraid you are looking for a discussion of truth in the philosophical sense, because you can't isolate the meaning of a single word that way. Nearly everyone agrees that facts are necessarily true; they disagree on what "truth" means. The de re definition of "fact" for any one person is "a true statement about the phenomenal world", but when one person writes out definitions for all the different usages of "fact", that person writes each definition de re with respect to his or her own definition of truth, so they all come out different. That's what accounts for all the different definitions of fact.