The certainty value of future tenses
What is it?

I don't know if I'm right but what I got so far is:
1. The tense with the highest certainty value is Present Tense Simple. It expresses unalterable plans or arrangements.
2. Future Simple - It expresses a prediction, a proposal or a promise
3. Present Continuous - it expresses definite arrangements or plans
4. The "be going to" future - it refers to the future of a present intention, a present cause or to the immediate future.

I'm only certain that Present Simple is in the first place, but I'm not so sure about the others. I'd appreciate it if someone could clarify it for me.

Question

The certainty value of future tenses
What is it?

I don't know if I'm right but what I got so far is:
1. The tense with the highest certainty value is Present Tense Simple. It expresses unalterable plans or arrangements.
2. Future Simple - It expresses a prediction, a proposal or a promise
3. Present Continuous - it expresses definite arrangements or plans
4. The "be going to" future - it refers to the future of a present intention, a present cause or to the immediate future.

I'm only certain that Present Simple is in the first place, but I'm not so sure about the others. I'd appreciate it if someone could clarify it for me.

Answer

This may be what it says in some grammar books, but the reality is more complex and much less 'clear-cut'.  The only way you can get a feel for the different ways we talk about the future is by reading and listening to real-life examples in context.

And I agree about the 'will' future - it doesn't usually indicate certainty.

Answer

I'm sure we all could have a healthy debate over this, but I'd drop "will [verb]" ("future simple" is a misleading phrase) down to the bottom of the list.  In spite of its surety, it's completely hypothetical.

Answer

Some linguistics argue that English has NO future tense. But in the order you have:

1. I dance tomorrow. - a statement of intention or "fact." So yeah, okay, pretty strong. But no plans are unalterable. :) Also, it is not the most common way to talk about the future (for instance, we do not say "It rains tomorrow").

2. I'll dance tomorrow - yeah, this can either be strong or weak. But see below.

3. I'm dancing tomorrow - I don't see this as any less certain as #1

4. I'm going to (gonna) dance tomorrow - see #3

Nevertheless, the common marker for future tense in English is 'll (or will).

Without the adverb "tomorrow," #2 is the only sentence that indicates some time in the future. Numbers 1 and 3 refer to the present (I dance. I'm dancing.), while #4 can mean the future as now: I'm gonna dance right now).

So, #1 may seem the strongest, but we do not usually refer to the future that way. #2 is the "normal" way to mark the future (with 'll used most often in speech, will, in written English). #3 is normally the way to say what you are doing right now in the present: Q: Watcha doing? Answer: Reading. (So-called simple present refers to a habitual action: I read every afternoon.)

Let's put it this way: if someone asks me, When are you gonna dance?

I am most likely to say.
1. tomorrow
2. I'm gonna dance tomorrow.

So, I'm dancing tomorrow AND I dance tomorrow, seem to be reserved for special emphasis or for clarification.

If someone asks me: When'll you dance?

I am may or may not use the same 'll (will) future marker when I answer:

1. tomorrow
2. I'll dance tomorrow/I'm gonna dance tomorrow./I'm dancing tomorrow.

But, I dance tomorrow ==> would be rare to answer in this fashion. usually only to clarify -when-.

Now -when- are you gonna dance?

Are you deaf? I dance tomorrow.