1) I don't know how good this product is.
2) I don't know how good this product may be.
I did find a question in this type, and they considered number 2 to be correct. I don't know why. Even I haven't found anything in relation to this on Internet.
Could anyone clear me? Which one is correct, or both? If both, then what's the difference?
May be leans the listener to believe that you might be considering or intending to use the product, than is.
1) I don't know how good this product is.
vs
2) I don't know how good this product may be.
What's the difference? First, let's look at some simpler sentences:
1a) This product is good.
and
2a) This product may be good.
In 1a (and 1), the speaker is stating a proposition about the product as a fact or opinion. It can even be the speaker's own opinion. 1a could be expanded by
1aa) This product is good. That is what the polls say, that is what my father believes, that is what the whole world believes. That is what I believe. I hold the proposition to be a fact, or it is my opinion about the product. In either case, the speaker has no doubt regarding the fact or opinion.
By contrast, 2a (with may) tells us that the speaker allows for the possibility that the product is good. This is called the epistemic use of 'may' and it is "concerned with the theoretical possibility of propositions being true or not true (including likelihood, and certainty)."
In 2a, the speaker is showing that he thinks the proposition (ie that the product is good) is a possible one. 2a can be expanded by
2aa This product may be good. The polls say that it is, my father believes it is, the whole world believes it is. But I am not sure what I believe. I hold that the proposition is possibly true.
Let's go back to your sentences.
1) I don't know how good this product is
is a statement of fact. Here it is not an opinion. The speaker is perhaps unfamiliar with the product or has not formed an opinion about the product. He is simply stating his ignorance concerning the degree of the product's being good.
2) I don't know how good this product may be.
is a statement that tells us that the speaker thinks it is possible that the product is good.
That is the main difference.
Besides this difference in meaning, 2 can be used to "make a concession" about the product:
2b I don't know how good this product may be, but I am still not going to use it or recommend it.
Other examples of these two uses of epistemic may are
II Jack may be in his room. I haven't seem him all day, that is probably where he is (It is possible that Jack is in his room.)
and
IIb Jack may be in his room, but that doesn't mean he will get any work done today. (I concede that Jack is in his room, but this does not mean he will get any work done today.)
simple present tense like 'is' ,"are" ......is used to express the situations which is always true,scientfic facts or habitual actions which are agreed by the whole!!
" I don't know how good this product is"
means that the product is being good for others, but you feel different ...
" I don't know how good this product may be"
means that rather the product is not as good as other simellar products for now, but if we make some appovement, it will be change to the future.(if youmake the exact approvement,it canges.But you don't know the way you approve it. )
