What is the grammatical difference between:
- I feel much happy now.
- I feel much happier now.
What is the difference between them in meaning?
Can I say that both sentences are correct?
- Your first one is incorrect, your second one is correct.
- The first one doesn't have any meaning, since it's incorrect.
- No; see answer to No. 1.
We don't use much with an adjective except in the comparative form (like happier). We use it with a noun: I feel much joy. With an adjective, we use an adverb such as very: I feel very happy.
The difference in meaning between I feel very happy and I feel much happier is that the first sentence isn't comparing its state of happiness to any other state. I feel much happier implies that there was some point in the past, or some hypothetical situation, that we are comparing the feeling to. That's why it's called the comparative form.
Consider these sentences:
I feel much happier than I did yesterday.
I feel much happier than I would feel if I had flunked the exam.
The first sentence compares the state of happiness to some other point in time. The second sentence compares the state of happiness to a hypothetical situation.