In the expression "It is certain", what does 'certain' add to the statement if not some attitudinal report, otherwise what's the utility of word 'certain', you could just say 'It is'. — Cavacava

You might say that "certain" is redundant here. But redundancy is useful to emphasize something to add strength to the statement. The utility of the word "certain" here is to emphasize that this is not an attitudinal report. In no way can it be interpreted as adding attitudinal report, as the intent in the usage is to emphasize that this is not an attitudinal report. Therefore the utility of the word is to emphasize that this report not be interpreted as an attitudinal report.

think your position is untenable. We are talking about certainty and uncertainty. How things are in themself can't be known, no objective viewpoint is possible. — Cavacava

I agree that it is very possible that how things are cannot be known. However, some people don't agree with this, and it is those people who use "it is certain..." to express how things are. I think my position on this is very tenable, the OED bears me out. It is those people who are using "it is certain" in this way, whose position you think is untenable. You might try to convince them of this, and make them stop using "certain" in that way, but I think that would be a futile effort. It's like an atheist who sees people using the word "God", and thinks the theist position is untenable, and therefore they ought not use "God". I am just describing what is going on, people use "certain" in this way, like people use "God" in that way. If you think that the things referred to by these words is non-existent, then that's a different argument. It doesn't make my position, my argument that people use these words in that way, untenable.

If you are becoming an ordinary language philosopher you may have to modify your moniker :razz:

Are you familiar with the method of Platonic dialectics?

Sometimes we have an idea of what a word ought to mean, how it ought to be used, and this preconceived notion clouds our apprehension of how the word is really used, what it really refers to. The Platonic method is to determine the nature of what the thing is which is referred to by the word, by examining usage, rather than accepting some preconceived notion of what the word ought to mean. So for example, in Plato's Theaetetus, they approach "knowledge" with the preconceived idea that knowledge must exclude falsity. However, in all the various ways that knowledge is described, none of them can exclude the possibility of falsity. Therefore it is demonstrated that the word "knowledge", in how it is commonly used, does not refer to something which excludes falsity. Knowledge, which is the thing referred to by the word "knowledge" does not really exclude falsity.

Now, we could argue that everyone misuses the word "knowledge" and they ought only use it when the possibility of falsity has been excluded, or we could allow that the preconceived idea that knowledge must exclude falsity is wrong, and start a new inquiry into what sort of thing knowledge really is, without that preconceived notion.

With respect to the topic of the op, uncertainty, if knowledge cannot exclude the possibility of falsity, then uncertainty rather than certainty is the essential, or integral part of knowledge.

If in doubt, don't go out.