Usage: Polite or Impolite? Past VS Present -- Part 3

DISTANCING with MODAL VERBS

The Modal verbs can be really wide as it can be used in many different ways to show different mood, time as well as possibilities (particularly in the conditionals, see earlier entries under the "Grammar" label).

There are 9 modal verbs in English:

Can & Could

Will & Would

Shall & Should

May & Might

Must

While the followings are often regarded as semi-modals or auxiliary verbs, which can be used in similar ways:

ought to & had better

used to

dare & need

do

going to

have to

One of the uses of modal verbs is to show politeness:

1. Can you help me open the door? I have no spare hands (Speaker is holding onto a pile of files).
2. Will you come with me? (Speaker turns around) This way please (speaker shows the way with his hand).

Examples 1 and 2 use the 'present' form, which implies that that distancing is not present, thus the speakers do expect a "Yes" as the response.

To show more politeness than the previous examples, we tend to use the 'past' version of the modal verbs: (Note that they are not really talking about the past)

1. Could you give me a hand?
2. Would you let me know your phone number, please? (add 'please' to make it even more polite)
3. Would you mind offering your seat to this lady ?(Speaking on behalf or a lady who is pregnant, even more polite when using "would you mind")
4. Could you possibly allow me to offer you a cappuccino? (Even more polite than "Could you allow" by using possibly)

With the exception of May:

1. May I offer you my jacket? (Cannot say "Might I offer")

Must is completely out of our concern here because it has nothing to do with politeness.

Resources:

http://en.wikipedia.org/wiki/English_modal_auxiliary_verb