|No, it's a matter of a language, and certainty means nothing more than lacking reasonable doubts. If you say there is no problem, then you must be certain that there is no problem. If you say that you can't be certain that you're 98% certain, then you must be certain that you can't be certain that you're 98% certain. If you claim that you don't need to be, then you are certain you don't need to be. A declarative sentence, by its very nature presupposes certainty.|
What is certainty in this context? Nothing more than a lack of a reasonable doubt. Indeed, you hit upon this when you say:
It doesn't affect the validity of my statement so long I have reason for thinking that it's highly probable that my statement is close to correct.And, of course, I can ask if you're certain that it's highly probable, I can ask if you're certain that it doesn't effect the validity of your statement so long as you have reason for thinking that it's highly probably that your statement is close to correct...I can even ask if you're certain that it was your statement.
The other problem has to do with what is correct. If you are to decide that something is probable that it's correct, you cannot assign a probability. You can argue that one statement is more probable than another to be correct based on evidence, but you cannot argue that any statement, by itself, is likely correct; i.e., you can only do so comparatively. To compare a probability is to know what 100% probability would be, which is to say: in order to assign a probability, you must already be omniscient.
Until you achieve omniscient, all you can do is make assertions that you see no reason to doubt.
For a simple example, when I woke up this morning, I turned off my alarm clock by pushing a small slide on the side of it, which I did without looking at what I was doing. I was certain that it would stop making the obnoxious noise that woke me up. I couldn't prove it would, but I was absolutely certain that it would. If it hadn't, I would have been confused, because the evidence would contradict what I knew about my alarm clock from previous experiences. There was no reasonable doubt that the slider wouldn't work.
If, perhaps, I smacked my alarm clock with a sledgehammer, then I wouldn't have that level of confidence that the switch works, at which case I'd revert to unplugging it, as my previous experiences with electric devices in general tells me that the alarm clock cannot make noise if it has no power. I am absolutely confident that cutting off all sources of power to this particular device will cause it to cease working. All that needs to be said: I have no reasonable doubts to this claim.
No numbers or probabilities are needed: you either have a reasonable doubt, or you do not.