Is it simply that Lewis didn't address the issue?

There are other stories and legends of people going to another world for various lengths of time. When they returned, their time in the other place sometimes matched the time they'd been away, and was sometimes more or less.  Lewis would have known many of these. 

The four siblings put their time and energy into their new kingdom. They had friendships with Talking Beasts and other non-humans, as well as contact with humans elsewhere.  Perhaps Aslan gave them the ability to forget their old lives until necessary. 

But what clues do we get in HHB?

Posted by: @tizzle

This is in contrast to every other book. For example, by the end of PC, Peter is well aware enough of home to know that their time is up and the four of them need to return to our world, and there are similar instances easily found in every other book.

Well, FWIW, that was right after Aslan had been talking to Peter and Susan. The implication is that he told them what he told Edmund and Lucy at the end of VDT, that they had grown too old to keep coming back to Narnia and they needed to get to know him in their own world. It wasn't something that just occurred to Peter. 

Of course, the "out-of-universe" explanation is that C. S. Lewis needed the Pevensies to gloriously reign over Narnia for at least a matter of decades for LWW to have a happy ending, but it wouldn't be very happy if they were mourning the home, friends and family they'd left behind, so he "magically" erased their memories. None of the other Narnia stories, not counting LB, require the protagonists to stay in Narnia that long, so Lewis had no need for that again. 

The children didn’t entirely forget their life here on Earth when they were in Narnia.  I think there were many times when they thought about it without mentioning it.  It didn’t mean that their life here was unimportant but rather that they had Aslan’s concerns to think about first.  There were things that happened here that concerned Aslan greatly such the illness of Digory’s mother. It is just that there were other things in Narnia that demanded the immediate attention of the visitors from our world. 

It's never explained how Narnia could have a separate time of its own. However long anyone would stay there (it could be possible in other worlds too), it would not take up of any Earth's time.

For instance, in MN, Uncle Andrew tells Digory that the box he received from Mrs. Lefay actually came from the lost world of Atlantis. It was supposedly swallowed up by water thousands of years ago. Later on in the story, Digory and Polly stumble upon Charn, which was a dying world. Jadis mentions that the sun in Charn had been red for thousands of years. It's never specified how long Charn existed before then, though.

I would not say that the children had lost their memory completely of Earth when they're in Narnia.

Posted by: @jasmine_tarkheena

It's never explained how Narnia could have a separate time of its own. However long anyone would stay there (it could be possible in other worlds too), it would not take up of any Earth's time.

No, but it's an important part of why the Professor believed Lucy's story about her first visit.

@jasmine_tarkheena

Posted by: @jasmine_tarkheena

It's never explained how Narnia could have a separate time of its own. However long anyone would stay there (it could be possible in other worlds too), it would not take up of any Earth's time.

For instance, in MN, Uncle Andrew tells Digory that the box he received from Mrs. Lefay actually came from the lost world of Atlantis. It was supposedly swallowed up by water thousands of years ago. Later on in the story, Digory and Polly stumble upon Charn, which was a dying world. Jadis mentions that the sun in Charn had been red for thousands of years. It's never specified how long Charn existed before then, though.

I would not say that the children had lost their memory completely of Earth when they're in Narnia.

The time of Narnia seems to be for the most part randomly connected to Earth’s time.  One cannot predict where and when the landing will take place in Narnia. It is a lot like the Tardis in Dr. Who. There were thousands of years that passed between The Lion, the Witch, and the Wardrobe and Prince Caspian. But the children could not predict the time or place of arrival.  The memory of those who travel between the worlds might be affected by the different times of the two worlds, but I think most of the recall would be retained. Travel between Earth and Narnia involves a lot of guesswork.  🙂

Posted by: @jasmine_tarkheena

It's never explained how Narnia could have a separate time of its own. However long anyone would stay there (it could be possible in other worlds too), it would not take up of any Earth's time.

Given that Time Dilation is a genuine phenomenon and explainable by the laws of physics it's probably one of the few fantastical things in need of explanation.

I think in terms of an in-universe explanation for the children's behaviour though,  I would put it at least part down to child-like naivety, and part down to a sort of dream-like aura that increases its influence the longer you stay in Narnia.... A bit like in the movie Inception where characters who have stayed in the dream world too long forget what it was like to be awake.

Obviously as with most of these sorts of topics though the real world answer is that CS Lewis wrote LWW in the style of someone telling a child a bedtime story and half making it up as they go along, so it can probably be attributed as a simple whimsical flourish to end the story with.

Thank you for all the great insights!

But what clues do we get in HHB?

Good question. The one thing that springs to mind is that Edmund beacons reflective as he remembers how he was a traitor when they were considering what to do with Rabadash. So in HHB he at least remembers the days of their arrival and how they acted.

Maybe, as others have said, Lewis intended to rewrite that section?

Well, FWIW, that was right after Aslan had been talking to Peter and Susan. 

I had to laugh at myself! Because of the capital letter naming conventions we usually use, I was trying to figure out what FWW was! Took a wile to realise you meant ‘For what it worth’!

Of course, the "out-of-universe" explanation is that C. S. Lewis needed the Pevensies to gloriously reign over Narnia for at least a matter of decades for LWW to have a happy ending, but it wouldn't be very happy if they were mourning the home, friends and family they'd left behind, so he "magically" erased their memories. None of the other Narnia stories, not counting LB, require the protagonists to stay in Narnia that long, so Lewis had no need for that again. 

But putting issue of time shifts to one side knowing that Narnian time and Earth time does not stick to any definitive rules other than Narnian time runs faster, my first line of thought is still that this is about remembering. And maybe the above is the best explanation. The Son of the Emperor  over the Sae is perfectly capable of doing what he likes, either in this world or another. And if that included lifting anxieties, or even memories of a past life and family, so be it. In another book it says:

“Forget about what’s happened;
    don’t keep going over old history.
Be alert, be present. I’m about to do something brand-new.” 

This doesn’t come naturally as many will know! And maybe not ‘remembering’ in the same way that we tend to, was Aslan’s gift to them; an opportunity to be alert and present and ready for something brand new.

I think it comes down to the kinds of stories Lewis was writing, and also how his concepts changed somewhat over the course of the series. LWW, the first one he wrote, is much more in the style of a fairy-tale being told to a child than the other books are. This is all we're told about the four children's thoughts of their own world during their reign as Kings and Queens, in that last chapter:

So they lived in great joy and if ever they remembered their life in this world it was only as one remembers a dream.

We could speculate that the amount of time they spend in Narnia reduces their ability to remember their own world, but as Lewis never leaves any of his other main Earthly characters in Narnia for that long, we really don't know for sure.

As for them not worrying about their parents missing them, the four Pevensies do already know, by this stage, that any amount of time spent in Narnia never takes up any time in our world. So even if they started out wondering how long they were going to live in Narnia, they would have been aware that however long they spent there, they'd arrive back in our world at the same time they left it, and so their family and friends wouldn't miss them at all. Perhaps that in itself helped them to let go of any anxieties and so gradually forget about "their life in this world"...

The problem with all this is that it then gets flagrantly contradicted by what Lewis wrote in The Horse and His Boy, which was written fifth in the series of seven. At the end of LWW, the four adult Pevensies are apparently so "Narnia-ified" and so forgetful of their own world that they don't even remember what the lamppost — "a tree of iron" — is, let alone that beyond it is the entrance to the world they originally came from. Whereas in HHB, not only do we have Edmund remembering being "a traitor" when he first came to Narnia, but we have Lucy, near the end, telling "the Tale of the Wardrobe and how she and King Edmund and Queen Susan and Peter the High King had first come into Narnia."

According to Lewis's later timeline, HHB is set only one year before the Pevensies' return to their own world, so unless they somehow had a complete memory wipe just in that final year, there is really no way to reconcile Lewis's original dream-like final episode of LWW with the way the same Kings and Queens think and behave in HHB.

Like the massive discrepancies between LWW and MN, I think it can only boil down to the fact that Lewis's own ideas evolved and changed as he continued writing the series and he apparently never went back over the earlier books he'd written in order to make sure he wasn't contradicting what he previously wrote. I very much doubt he was trying to make any theological points in this, either... it's just sloppy plotting, and there's no way around it. But it doesn't stop me loving the books to bits anyway!!

Posted by: @courtenay

According to Lewis's later timeline, HHB is set only one year before the Pevensies' return to their own world, so unless they somehow had a complete memory wipe just in that final year, there is really no way to reconcile Lewis's original dream-like final episode of LWW with the way the same Kings and Queens think and behave in HHB.

I think that timeline should have been very different. Instead of one year between HHB and the Pevensies' return, a gap of twenty or thirty years would have made more sense. It would have given them more time for their language to change, for more interaction with neighbouring countries, and for them to forget their past.

I agree about some sloppy plotting, too, and about Lewis not having gone back to avoid contradictions.

And I also agree about loving the books to bits anyway!

Posted by: @varna

I think that timeline should have been very different. Instead of one year between HHB and the Pevensies' return, a gap of twenty or thirty years would have made more sense. It would have given them more time for their language to change, for more interaction with neighbouring countries, and for them to forget their past.

Well, as I know has been discussed here before, the timeline does have significant problems, including several major discrepancies between it and the actual books. It was first published in Past Watchful Dragons by Walter Hooper, who worked with Lewis as his secretary during the last few months of Lewis's life. Hooper doesn't say anything (if indeed he knew) about when and how Lewis wrote the timeline, except that it was after he'd finished writing all the books. So it's not really clear how far it should be taken as "canon".

And I also agree about loving the books to bits anyway!

Hopefully we all do!  

So they lived in great joy and if ever they remembered their life in this world it was only as one remembers a dream.

Yes I had forgotten this reference!

Whereas in HHB, not only do we have Edmund remembering being "a traitor" when he first came to Narnia, but we have Lucy, near the end, telling "the Tale of the Wardrobe and how she and King Edmund and Queen Susan and Peter the High King had first come into Narnia."

Yes.

I think that timeline should have been very different. Instead of one year between HHB and the Pevensies' return, a gap of twenty or thirty years would have made more sense. It would have given them more time for their language to change, for more interaction with neighbouring countries, and for them to forget their past.

I like this. It makes a lot of sense. Even another 10 years could serve as a way to ease the plot inconsistencies without messing much with the storyline. 

I’m really enjoying hearing from people here who have such great insights! Thank you!

Even ignoring the disputed timeline the issue remains. In PC they said the orchard was planted by the moles just before the ambassadors came from Calormen and that was only a year before they went back to England.  In HBB Susan said that before Rabadash arrived the moles were planting an orchard. I suppose you could hypothesise there were two orchard plantings, with emissaries from Calormen arriving after each, but it seems very contrived. 

Posted by: @hermit

Even ignoring the disputed timeline the issue remains. In PC they said the orchard was planted by the moles just before the ambassadors came from Calormen and that was only a year before they went back to England.  In HBB Susan said that before Rabadash arrived the moles were planting an orchard. I suppose you could hypothesise there were two orchard plantings, with emissaries from Calormen arriving after each, but it seems very contrived. 

I see the differences between the two orchard plantings, and the possibility that the books date the same occasion in two different ways.

But if we ignore the disputed timeline, we have no dating of the planting. The books don't say that the ambassadors came a year before the Pevensies went back to England. The books don't say anything about when they went back.

I think Lewis had an agreement with an editor at his publisher's that they should find a time to meet up and talk about what ought to be done about lack of consistency in the Chronicles. But as he died before they had time for any such meet up, nobody knows what they would have talked about if it had happened ...

We just have to live with the inconsistencies. It can be fun to try to make in-universe explanations for some of them, but such explanations can easily become almost a sort of fan faction. Which is not canonical.