Is there a single word that means "almost certainly (but not technically 100%)"?

Question

I'm looking for a single word that means "almost certainly" but leaves room for 'technical' or 'philosophical' doubt. That is, something like 99.99999...% certain. Or "close enough to certain that we don't need to get hung up on it".

• probably doesn't work because it just means over 50% – way too low.
• indubitably doesn't work because it literally means "undoubtable", i.e. its definition explicitly excludes the possibility of any doubt.
• definitely, certainly, doubtless – strictly speaking, these do not allow for any doubt either (even though they are often used in casual speech for things that aren't truly certain). I want a word that, when used precisely and literally according to its dictionary definition, perhaps in a philosophical/technical/engineering context, actually means "certain, except for the usual 0.00000...1% doubt".

The word should acknowledge a shade of doubt without getting stuck on it, if that makes sense. I don't know if such a word exists, but it seems odd to me if it doesn't, as it seems like it would be very useful in epistemological and engineering discussions.

I guess "beyond reasonable doubt" is a common phrase that means roughly what I want, but I'm wondering if there is a word that (a) is a single word or simple compound, and (b) is used in more of a philosophical/technical/engineering/critical thinking context than a legal one.

Answer 1

If you have no specific potential doubt in mind then it's 'as certain as blow it'. But that may be too casual/informal for your purpose.

If something is 99.999.... certain, then it is as 'near certain as makes no matter'. but if the difference makes no matter, then you have no reason to doubt it at all. And in that case, you may as well say it is certain.

The point 0.0000000...... chance of being wrong is so small that you never get to a 1 at the end. If if such an improbability were to occur, nobody could possibly calculate its probability. It would be like the probability of all the atoms in the chair you are sitting on moving upwards at the same instant. We are talking about the infinite improbability drive in 'A Hitch-hiker's Guide to the Galaxy. After all. 0.00000.... is infinite improbability.

Short of that, 'nearly', 'almost' or 'virtually' certain are all fine. In real life, if the virtually impossible does happen, it will not help you to plead that in fact you were right on the grounds that it it was, in fact, virtually impossible, unless there is a precisely calculable probability. In which case, I guarantee it will be at least 1% and probably more.

Answer 2

Since you're mentioning engineering, "with infinitesimal likelihood to fail", "tangentially close to target", and "asymptotically near certainty" could all be candidates for what you mean.

Note that these expressions really only fit into a scientific context, and I wouldn't expect to hear them in layman usage.

I do wonder if there's an antonym for "infinitesimal" which could be used here.

Answer 3

VIRTUALLY
ADVERB
1 as submodifier Nearly; almost.

Source: Lexico

As in the statement “I am virtually certain.”

Answer 4

From Dictionary.com:

Presumptive [adjective]

1. affording ground for belief or presumption: presumptive evidence.

2. based on likelihood or presumption: a presumptive title; the presumptive nominee.

3. regarded as such by presumption; based on inference; assumed: a presumptive case of pneumonia.