If we use implausible as a stronger version of improbable, meaning "seemingly (but not absolutely) impossible", is there a word equivalently stronger than probable, e.g. "seemingly (but not absolutely) certain"?
A diagram of the level of certainty that I ascribe to various words:
You can say almost certain, very likely, good bet, confident of, etc, but is there a single word?
Conclusion: thanks for all the suggestions. Yes, I do understand that possibility, probability, and plausibility have different connotations regarding belief, information, truth, etc. I stand by my assertion that they each can be roughly measured on a 0-1 scale, even if the qualities being quantified are not exactly the same.
Best Answer
If we understand implausible to express "I cannot believe it", then it seems to me that its strong antonym should express "I cannot doubt it": so I propose indubitable.
A weaker contender might be unquestionable.