watch vs see depends on tense?

Question

I understand the difference between watch and see and that's not what this question is about. My question is why does the choice seem to be driven by tense at times? Consider the following examples:

I saw this movie last night.

I will see this movie next weekend.

I have never seen this movie.

I am watching this movie right now.

As you can see, it's the same action in different tenses and yet see seems a better fit when it's in the past tense or future whereas watch sounds better in the present tense. I just want to understand what drives this. To add to the confusion, there's this:

I was watching the movie.

This one takes a watch despite being in the past tense. I know it seems stupid to think of watch vs. see as a tense-driven choice because no grammar book ever said that. But the pattern is hard to ignore, no?

Answer 1

Perhaps, and this is only speculation, the present continuous tense be+see+ing is generally avoided in affirmations such as

I'm seeing Alien 4 tonight

and

He's seeing a film at this moment.

The verb see also means to meet someone, and said aloud without any previous context, it might be understood that there's an appointment to meet up with someone called Alien, or they are dating someone called Film. I know it's unlikely, as we are all equipped with common sense and personal experiences, but the first two structures do sound a little odd nevertheless, whereas I don't find any ambiguity in the following example:

We were seeing a movie when suddenly there was a loud noise.

The structure be + Verb + ing expresses volition, and there is no significant difference, in terms of volition, between “I'm seeing a play” and “I'm watching a play”, the latter being only preferable if referring to a television broadcast.

Having said that, the present participle seeing + a movie often follows a preposition, and the main verb like. In the Ngram chart below, the clear frontrunner is after seeing a movie with of seeing a movie and like seeing a movie not far behind.

The results shown with the verbs are and were seem to confirm that native speakers tend to avoid the progressive tense with see a movie. This ambiguity, which I mentioned earlier, is easier to eliminate in print and with context, but maybe this infrequency of usage compared to watching a movie, is down to idiomaticity and little else.

(Watching a movie is represented in blue, while seeing a movie is in red.)

If we compare the following results with to see a movie, Ngram produces the following chart.

Answer 2

In a comment, FumbleFingers answered:

I'll watch this movie on video tonight, even though I saw it in the cinema last year is perfectly normal English. The watch/see distinction is similar to listen to/hear (the first implies volition much more than the second). That's why we normally say I'm listening to a great song on the radio (because as with watching a movie, it's a deliberate act, and we'd like to think we're in control of whatever we're doing at any given moment). But if you saw a movie or heard a song in the past, maybe it's just something you happened to do (or that happened to you).

And then followed that up with:

I'm sure there are others who could explain it much better than me, but if I was going to take the time, I'd amend this previous answer and cite it as a duplicate. Your question is essentially a specific minor detail arising out of the basic distinction between the two verbs (perhaps with a small element of "idiomatically established" preference).