Using the comma as a list of things vs two related thoughts

Question

Recently I sent a mail wishing a friend well. I ended it with the following sentence.

Please take care, and call me if you need anything.

The comma was included because the two were separate thoughts with the latter as an add-on to the former. Consider it without the comma.

Please take care and call me if you need anything.

While grammatically correct, it sounds like a to-do list--please do the following things: (1) Take care, (2) Call me if you need anything.

Would you agree? I see this cropping up in a lot of writing here and there.

I phoned my wife, and slept for 2 hours

seems to be a description of the list of things I did this afternoon, while

I phoned my wife and slept for 2 hours

sounds like I'm reporting a very boring conversation.

Answer 1

Structurally, there are two different ways to write things.

I phoned my wife and slept for two hours

lists the two activities done in the form of A and B, while

I phoned my wife, and I slept for two hours

joins two related complete sentences using an optional joining comma and and so that we do not write them separately.

I would not write

*I phoned my wife, and slept for two hours.

Answer 2

I don't think the use of the joining comma (R L Trask's term) need ever create ambiguity which cannot be resolved by the context.

Answer 3

I'm not clear what's being asked here. As OP seems to realise, omitting the comma in these examples may imply the preceding and following elements are more closely connected.

Thus "I phoned my wife and slept for 2 hours" could (somewhat perversely) be taken to mean that the two actions were actually concurrent. Easily avoided by either including a comma, or (more fluently, IMHO) using then instead of and.

There is a general tendency going back over many decades to reduce punctuation. Arguably this leads to more contexts where such "unintended" conflation can occur in the mind of the reader.