I don't have much time, but this is really burning my brisket, so I'm going to go ahead and slap this out.

LTT is NOT a construct. The construct theory fails Occam's Razor- it's overcomplicated and doesn't fit the mechanics of Jordan's world as he's defined them- it depends too much on magic to work. In theory, there is much discussion of how "normal" definitions of insanity don't apply, since it's a fantasy series- no, Jordan is at pains for real-world parallel.

Why does the LTT is a Construct fail?

What is a personality in Jordan's world?

There are two elements: Soul and memory.

The way souls are used, Jordan quite patently does not subscribe to tabula rasa- the soul represents a base personality type and emotional matrix that interprets its experiences and "Grows" a personality from them- meaning the memories "alter" the growth of the soul into patterns that form the personality.

What situation is there in Rand's head?

Rand has two independent memory sets, both colored, shaped, and prioritized by the same soul- meaning they're both 100% compatible with the soul.

Personality is soul+memory.

Same soul, same memory=same person.

Soul combined with this lifetime's memories: Rand.

Soul combined with AOL lifetime's memories: Lews Therin.

As long as the Rand body contains the Lews Therin memories and the Lews Therin soul, there must be a resultant Lews Therin personality, much as the combination of the Rand memories and the Rand soul gives the Rand personality.

Is the redundancy clear? There HAS to be a Lews Therin personality as long as Lews Therin memories are present.

Two objections might appear: One, why doesn't Rand integrate the memories of Lews Therin, and two, where are the Lews Therin memories coming from?

Rand and Lews Therin had two radically different upbringings, one is an educated, erudite man of strong will who lived three hundred years in a very sophisticated culture, one is a farm boy who lived nineteen years in a medieval farmer's community and about two years in a High Medieval/Renaissance culture.

The Lews Therin personality must exist and be noticeable to Rand precisely because, despite their identical basic emotional matrix, Lews Therin would have differing opinions to Rand on many issues, opinions Rand could clearly label as not his own.

It is significant that the Lews Therin voice "grows" throughout the series, and more significant what memories transfer to Rand versus what "thoughts" he's aware of from Lews Therin.

As Rand gains more of Lews Therin's memories, or gains access, the "voice" grows- because the memory set is becoming sufficient to "qualify" as the Lews Therin personality. Before, he could have snatches- because as we learn from Mat, with memories comes the understanding that shaped/interpreted those memories, the entire reason he can speak and understand the Old Tongue in the first place.

Rand is significantly not aware of Lews Therin's memories, or Lews Therin as a separate personality, at those times both personalities are in harmony/agreement with each other. When confronting Taim, Rand lists off atrocities of the Forsaken- and notes that he knows those can't be his memories, yet he has no sense of Lews Therin commenting or offering them up. The same happens when listing atrocities of Sammael to Sammael's messenger. He even comments that the pain of what Lews Therin had seen "burned across the Void as if Rand's". The significance is that both Rand and Lews Therin confronted with those scenes underwent an identicual visceral reaction- this is what shapes memories "in common."

In contrast, Rand is aware of Lews Therin humming at Caraline Damodred, a woman who makes Rand's heart clench. Rand is aware of the separateness of Lews Therin's "thoughts" _when_ those_ thoughts_ are_ not_ in_ harmony_ with_ Rand's_own.

This is why Rand is torn between whether or not Lews Therin can "see" him. Lews isn't separate from Rand. He's Rand operating out of a different upbringing and background memory set. So, when Rand's confronted with something and considers one action immediately, he "notices" "Lews" considering another. Does Lews see? No more than Rand.

I recall a science fiction story from a philo class I took. A man ends up with his organic brain and a robotic copy each remotely controlling his body, and every six months hits the switch that determines which is "actually" in control. Because they're identical, he has no sense of disorientation and switching between the two- whatever one wishes to do, the other wishes to do as well at the exact same time, since both "minds" receive sensory input. ie, it seems to both minds that they are in control.

At the end of the story, he hits the switch- and something has gone wrong. Perhaps a neuron died, or a component broke down- but the minds had gone out of synch. One mind had then become a prisoner in its own body.

Rand and Lews Therin are in a similar situation. Rand only notices Lews Therin's thoughts when they're "out of synch" with his own, and this generally manifests as a voice. When they are in synch, Rand's absorbing memories without any awareness whatsoever- because the memories are "intuitively" correct in their compatibility.

There is three-fold relevence here.

First off: Rand's isolation, followed by excessive physical training in tDR on.

Rand could have become a blademaster inside of five years, studying under perhaps the best blademaster in Randland. Instead, he becomes one in little more than one.

Is it because it's fantasy? No, Jordan doesn't write like that.

Lews Therin was a blademaster, with similar proportions to Rand- we're told they have the same height, and during Rahvin's attack we learn Lews had slightly longer fingers, etc. But their proportions are the same- the bodies are very similar.

In order to integrate the "early" extra memories, Rand needed to develop a point of commonality. The obsessive bladework allowed the Rand half to gain enough muscle and skill to tap into Lews Therin's ability, and the Lews Therin half was able to "learn" the subtle differences of Rand's body in order to use his skills- with both personalities in harmony, Rand is able to access the full range of Lews Therin's skills in the Rand body, without any sense that they are not Rand's own.

It is significant that only very late in this process can Rand draw from Lews Therin, or play music Lews Therin has heard.

Lanfear was surprised Rand played the flute, and when Rand found it after a long period, he didn't play very well. This isn't how playing a music instrument goes- you retain almost all your skill, you lose muscle tone and wind.

But the Lews Therin half had no experience in playing instruments, so the gestalt physical skills needed more fine integration.

I now need to check, but it occurs to me that it is after mastering the blade that Rand begins wondering where his flute his- subconsciously wanting to fine-tune his shared physical set?

I would propose this is part of the point of Rand hardening himself- Lews Therin was not hard, and it has the additional ability of dissociating their emotional reactions. If Rand doesn't react and Lews does, then there's no commonality, preventing synthesis of personalities.

I would put forward this is why the central importance to the Wheel of Cadsuane teaching Rand laughter and tears- without laughter and tears, there is no shared emotional matrix to allow commonality with Lews Therin, therefore disallowing Rand access to Lews Therin's memories, leaving him only with Lews Therin's thoughts.

Lews Therin's madness is easily explained out of this as well- the Rand half still, until recently, had "primary" control of the body, meaning he's trapped, though he can perceive- so his thoughts are turning inwards more often than not.

Further points:

The Taint-degradation I'm going to note briefly.

Osan'gar and Aran'gar note that they lose memories while "asleep"- meaning dead (the short sleep). RJ has also commented Sammael is toast, etc, though he can be reborn. This suggests that death erases souls.

This also suggests that the Heroes, who we already know don't go into the "soul pool", are a special case whose memories are "retained" in tel'aran'rhiod and can be reclaimed between lifetimes. Perhaps their souls aren't white-washed, and perhaps the Wheel "flash-imprints" tel'aran'rhiod with their memories, explaining why Birgitte's losing hers as she's farther away from tel'aran'rhiod- her memories are there, not in her body. Her body has a temp folder that's slowly being emptied for new input.

With Taint degradation, Rand would be gaining access to memories of ALL his past lives, because they're not separated for Heroes who are dead. This is NOT the case.

The alternative is the "LTT trapped his soul in Dragonmount" theory- to which I subscribe and which I may post here again soon if it doesn't turn up. The short version of it: the Rand body was stillborn but compatible with (or the intended body of) the Dragon soul- so the soul recognized no difference between the mountain and the body on it. The soul was not wiped clean, nor did it have whatever barriers heroes get- but after 3000 years, it'd be a bit batty and probably comatose from total sensory deprivation.

Hence Tar Valon and even the ward around Callandor- made from stone from all over the world, it could easily have incorporated a piece of Dragonmount and only allowed through what the ward recognized as "the same"- Rand's body, yet another container compatible with the LTT soul.