My friend and I have an ongoing debate over which word communicates a stronger sense of conviction.
For example, when I'm 98% positive of something I often say "I am confident that's how it happened, but I'm not sure."
He argues that it should be the other way around.
All the dictionaries that I've consulted have used one word in the definition of the other. So far, they're starting to look like synonyms. Is this debate even resolvable?
They are synonyms, but that doesn't mean they are exactly the same.
According to Dictionary.com,
Sure, certain, confident, positive indicate full belief and trust that something is true. Sure, certain, and positive are often used interchangeably. Sure, the simplest and most general, expresses mere absence of doubt. Certain suggests that there are definite reasons that have freed one from doubt. Confident emphasizes the strength of the belief or the certainty of expectation felt. Positive implies emphatic certainty, which may even become overconfidence or dogmatism.
Unfortunately, almost no online dictionaries discuss connotations of words, or this would be more easily answered.
Sure and confident are very similar -- in fact, the first word in the first definition in The Free Dictionary (TFD) for sure is confident.
According to The Free Dictionary, in discussing the definition and synonyms of sure:
definition of sure: Confident, as of something awaited or expected: I am sure we will win the game.
As a synonym for sure, TFD says:
Confident suggests assurance founded on faith or reliance in oneself or in others: "It goes without saying that a smiling, confident person will do better in an interview than a surly one" (Barbara Ehrenreich)
Many -- not all -- of the quotations from literature given by The Free Dictionary support this nuance. For many quotations, see TFD,sure; and TFD, confident
Jane Austen, Pride and Prejudice I know of nobody that is coming, I am sure, unless Charlotte Lucas should happen to call in-- And I hope MY dinners are good enough for her.
Upton Sinclair, The Jungle: Jurgis was confident of his ability to get work for himself, unassisted by any one.
How does this answer the OP's question? Confident suggests a basis for the expectation -- one's own work or abilities or a close knowledge of someone else's abilities. Sure has a weaker basis -- for example, the speaker in Pride and Prejudice merely expected that no one was coming. Thus, confident is stronger -- although confidence can be misplaced. Sure is weaker -- although it may turn out to be correct.
Well here are my thoughts. I think confident sounds more on conviction side. Confidence is something which you get from your own inner strengths and abilities while sure is more dependent on external factors. For example we usually say are you confident enough to pursue this goal. Here it is asking the person to say yes or no on the basis of his/her own ability. While if we ask are you sure this technique will work (to solve a problem) we say on the basis of what we have known from others' (and sometimes our own) experiences like yes it worked in case of my friend so I'm sure it will work for me as well.
Others have given the dictionary definitions of sure and confident, so I'll just proceed with an answer based on usage.
If someone says, "I'm sure I left it here somewhere.", the literal meaning is that they are confirming its location. However, in popular usage, it conveys uncertainty, so much so that it is the subject of an internet meme. It is also common to come across statements like "I don't remember any of it but I'm sure that's how it happened."
On the other hand, "I'm confident that's how it happened." is a statement that doesn't convey uncertainty.
Compare the google searches for the following phrases: - "don't remember but I'm sure" yields about 1,300,000 results; but - "don't remember but I'm certain" yields none.
My friend and I have an ongoing debate over which word communicates a stronger sense of conviction. ... Is this debate even resolvable?
According to the above, confident communicates a stronger sense of conviction than sure in the context of your sample sentence.
You are asking which word is stronger, which assumes that they are points on a continuum. What you will find is that both represent a range, and those ranges overlap. It's like asking which is greater, a number in the range 4-7 or a number in the range 5-9? Or even comparing 5-7 with 4-9, where one range is entirely within the other. Each person is likely to have their own idea of where in the range each word should fit. As such, just about any answer is correct.
Dictionaries will always leave something to be desired. The something is context. For example, contrast the discussion of the synonymity of "sure, certain, confident, positive" from American Heritage with the discussion quoted by @medica from Dictionary.com:
These adjectives mean feeling or showing no doubt. Sure and certain are frequently used interchangeably; sure, however, is the more subjective term, whereas certain may imply belief based on experience or evidence: "Never teach a child anything of which you are not yourself sure" (John Ruskin). "We went that early because we were certain it was the only way we would ever get a seat" (Ann Patchett). Confident suggests assurance founded on faith or reliance in oneself or in others: "It goes without saying that a smiling, confident person will do better in an interview than a surly one" (Barbara Ehrenreich). Positive suggests full, emphatic certainty: "We were young, and I was positive nothing really terrible could happen to us" (Nora Roberts). See Also Synonyms at certain.
Both discussions are expositions of the impressions of people who have studied the uses of the 'synonyms' in context, such as is provided by the quotes given.
Connotations are meanings associated with words in context. While some connotations may be commonly associated with a given word, and those connotations may over time become part of the denotation of the word, other more transient connotations may temporarily modify the meaning of a word or words wildly--in context.
For example, an anecdote I don't accurately recall goes something like this:
A Philosophy Professor: "In English, a double negative often intensifies negation. A double positive never does."
Student from the back of the class: "Yeah, sure."
The connotation of "yeah, sure" in context is often such as to render the two positives wholly negative, as an expression of disbelief. That is not invariable, however; sometimes, in context, a cigar is just a cigar, and "yeah, sure" simply expresses the speaker's agreement with what has just been said. The meaning, and the connotations, depend on the context.
All of that is to this point: you're getting it wrong when you say you and your friend are having
an ongoing debate over which word communicates a stronger sense of conviction.
The pedantic truth is that words alone do not communicate at all. Only words in context do. Communication consists of two parts: expression and interpretation. Communication does not exist without both parts, even if the person expresssing something and the person interpreting that expression are one and the same.
So, whether 'sure', or 'confident', communicates more of a sense of conviction depends upon the context, and a large part of that context is what is intended by the speaker along with how the speaker's expression is interpreted by an auditor.
Merriam-Webster's Dictionary of Synonyms (1984) has an interesting take on this question, in part because it assigns sure to two very different sets of synonyms, only one of which includes confident. First under the grouping led by confident, it has this:
confident, assured, sanguine, sure, presumptuous are comparable as applied to a person or to his temperament, looks, manner, acts, or utterances with the meaning not inhibited by doubts, fears, or a sense of inferiority. Confident may imply a strong belief in oneself or one's powers, but it nearly always implies freedom from fear of failure, frustration, or attack and, as a corollary, certitude of success, fulfillment, or approval. As a rule it is not a depreciative term, and often is complimentary [examples omitted] ... Sure implies that one's freedom from doubts or fears is rather the consequence of certainty or or of complete confidence in one's skills than of temperament or health. The word also often connotes a steady and disciplined mind, mental or emotional stability, or unfailing accuracy [examples omitted]
But sure also shows up in a grouping that it leads:
sure, certain, positive, cocksure mean having or showing no doubt. Sure and certain are often interchangeable. But sure frequently emphasizes the mere subjective state of assurance; certain often suggests more strongly a conviction that is based on definite grounds or on indubitable evidence [examples omitted]
So in Merriam-Webster's telling, confident is closer to an attitude and sure is closer to a conviction. It's noteworthy, too, that MW describes sure as arising out of "complete confidence," as though confident at its highest level yields sure.
S.I. Hayakawa, Choose the Right Word: A Modern Guide to Synonyms (1968) draws an even sharper distinction between confident and sure, parking confident under optimistic, along with hopeful and sanguine, but making sure the lead word of a group that includes certain, definite, doubtless, and positive. Here is Hayakawa's treatment of the two words:
optimistic, confident, hopeful, sanguine These words refer to positive frames of mind. ... Confident, by contrast, stresses conviction and certainty about the future; the word, furthermore, may imply a conviction based on a knowledge of the facts: [examples omitted]. The word may also suggest self-assurance: [example omitted].
sure, certain, definite, doubtless, positive These words all mean free from doubt or uncertainty. Sure and certain are used interchangeably in most contexts, but certain may emphasize the indisputable character of what is referred to, implying that whatever is certain is subject to reasonable debate. Sure is more indiscriminately used. [Examples omitted.] Both words, but especially sure may serve as polite substitutes for a hopeful but less-than-certain attitude. "I'm sure he'll be here on time" can mean "I think (or I hope) he'll be here on time."
I think it's important to bear in mind Hayakawa's observation that people often use sure when they don't mean it. In the example he points to, they do so out of politeness. But people also often use sure (or confident) when they don't mean it, out of a desire to exaggerate or mislead. Ultimately, the breadth of the sliding scale of assuredness or certitude that both confident and sure comprehend dwarfs any fundamental difference in degree of certainty that the two words may have.
