I know this is a very old thread, but I wanted to point out one thing.
As stated in
Why did Lavos Destroy Zeal then the world in 1999, Lavos three times acted out. Destroying Zeal, defeating Magus, and destroying the world.
The first can be seen as a reaction or reflex. Zeal was tapping Lavos' power like a mosquito drinks the blood of it's victim. Eventually, the victim notices what the mosquito is doing and reacts by trying to squash the mosquito or itch the wound. This can be seen when the Mammon Machine is moved to the ocean floor. The proximity of the machine was like a person suddenly feeling the posion of a mosquito in their arm. As for Schala's growing insanity, that can mostly be equated to her prolonged proximity to the overwhelming power of Lavos. Like the ring from Lord of the Ring or standing next to a radioactive rat. Both slowly changed you for the worse, but you wouldn't call either sentient.
The second action is also a reflex. Magus tried to summon Lavos and kill him. You wake me up in the middle of the night and try to kill me, it's a fair assessment that I'm going to take a swipe at you. Nothing out of the ordinary there.
So far Lavos has demostrated nothing sentient. However, destroying the world in 1999 is a sentient action, not reaction. As stated in the document at top from this very site, Lavos more than likely emerged because the world was reaching a point where it could interfere with Lavos' plan. Both the allusion of a plan and the ability to recognize an
impending threat, as in foresight, are clear signs of sentient intelligence. It is clear to me that Lavos is intelligent. But sheer intelligence does not make a creature sentient. You can teach a monkey what a gun is and how to use it. You can not do the same for a cow or dog. And while both cow and dog can be taught to fear a gun, neither the cow, dog, nor monkey probably can infer the increased danger of ten guns versus one gun. They have simply learned that gun equals pain. More guns equal pain. And even more guns equal pain. The same pain, not more pain, not more threat. Just the original threat. Lavos, however, recognized the oncoming threat of humanity. And decided to enact the second phase of it's plan. For me, these are evident signs of sentient thought within Lavos.
In retrospect, just because a creature is sentient, doesn't mean it will go against it's natural instincts. Humanity is plagued with smokers, crack addicts, sex addicts, and gamblers. All those people know and accept they don't have to fall to their addictions and do anyway. So Lavos might as well know it is destroying world after world, but is compelled to do so by an deep, overriding urge to propogate. And by the same token, knowing doesn't mean it cares.
On an aside, in the original discussion, Doctor Shaft said this,
Lavos is above and beyond us, and I do not agree. Lavos was not a super being. The ability to control time is nothing special, given the discoveries in the modern times about the very plain nature of Time. Lavos, at the core of its plan, desires to collect the perfect DNA, it's more probable that after millions of years of absorbing the collected superior DNA from X number of planets, that the ability to control time and space emerged naturally. Along with the immense magical abilities and overwhelming power. The creature is basically performing selective breeding on itself anyway.
On a final aside, just because Lavos never said anything to anyone is a very poor excuse to write off its sentience. How was it going to talk to you? Through it's eye? (Yeah, yeah, psychic, magic, etcetera. You get the point though) A creature that possibly trillions of years old doesn't need and more correctly doesn't desire to talk to
you.