Really, aliens? You invade a planet that is made up of stuff that can melt flesh off your bones? You deserve to be defeated by Joaquin Phoenix and a baseball bat. Stupidest invasion ever.
Invasion score: FWell, actually, it's not that stupid after all. There are two reasons for this: 1) habitable planets are not as common or as easy to get to as we would like, and 2) humans, who consider themselves to be intelligent creatures, routinely invade or inhabit lands that present serious challenges to our well being. I'll expand these two points below:
I. Habitable Planets
There may be billions of habitable planets out there, but we also have to remember that those planets are far away from one another. Even an intelligent species with technology far surpassing ours would have trouble traveling between the stars. Their access to other habitable worlds, then, would be severely limited. They might have a few hundred to work with in a reasonable amount of time (even if they do happen to have FTL drives).
With this limitation on an "empire," it's not unrealistic for aliens to shrug off the dangers of a world covered in materials they are allergic to -- water -- in an attempt to grab resources they can use -- land, metals, fuel, air, and so on. Earth may not be an ideal target for the aliens of Signs, but it is certainly the result of limited options. If you need more space to inhabit, then you're going to go where such things are available. Humans do this all the time. We live in deserts and places where it gets so cold we have to cover ourselves in layers and layers of clothes. We'll get back to that in a minute. For now, on to point two.
How many nations have tried to invade Afghanistan? Enough that people look at U.S. attempts to conquer the nation and see pending failure. All kinds of countries have invaded other countries and quickly found themselves on the losing end because the "enemy" proved to be more formidable than originally thought or was smart enough to use the terrain to their advantage. In the case of Signs, we can assume that humans figured out the aliens were allergic to water pretty quick and started loading up fire engines and sending civilians to lakes and rivers with super soakers and water balloons. The fact that none of this was in the movie is a separate issue from the criticisms about water allergies.
It's also worth noting that the aliens are not deathly allergic to water. Some people assume that they are because the one alien in the movie gets killed more or less by water, but remember that he was hit with quite a bit of the stuff. One glass or two weren't involved. Dozens of glasses of water were sprayed all over his body. This would be like getting stung by hundreds of bees, which would kill most humans anyway. Yet, remarkably, we still live in all kinds of places where bees and other stinging/biting/spraying creatures are prevalent, and even where dangerous and aggressive bees (i.e., Africanized bees) have made their homes. To be fair, we created the Africanized bee, which is now "colonizing" northwards; the aliens in Signs were working in the opposite direction. Regardless, the fact still stands that humans are not all that smart either.
But on to my third point!
While many people have criticized Signs for the fact that the aliens invaded a planet full of stuff they're allergic to, few have actually talked about the issue of dress. The problem, as it appears to me, isn't that the aliens are allergic to water; it's that they came to Earth dressed for the wrong occasion. There may be a lot of interesting (though not necessarily good) reasons for this, but none of them are present in the film. It's possible the aliens have no sense of nakedness, which would align them more with "the animals" than it would with humanity, but this seems to me to be a somewhat absurd argument to make precisely because they do have some understanding of survival in hostile environments (i.e., they have spaceships, which protect them from the vacuum of space).
The question, then, is this: why don't the aliens in Signs wear something approaching a protective covering? Whether this be in the form of armor or some kind of special wet suit, you'd think these creatures, who have the ability to travel great distances in what seems to be a reasonable amount of time, would have developed something to protect them, at least temporarily (during battle), from materials they are allergic to. This logic would also prevent the immediate revelation that they are allergic to water, which would give the aliens more time to secure themselves on Earth and strategically take down our defenses and leadership. But they don't wear protective covering at all. Why? I would hazard to guess that they don't because they intend to mount an immediate and swift attack on our infrastructure -- a fact that is also believed by the characters in Signs. Doing so in armor might present challenges. But there is so little that we actually do know about the aliens that it's hard to say what kind of logic they were operating on.
And that's really the crux of it: Signs never was a film about an alien invasion. Not really. It was a film about a broken family surviving catastrophic disaster. The alien invasion is just the catalyst for their growth and development. In a way, Signs is really one of Shyamalan's most clever productions, since it uses foreshadowing in a brilliant way. Every eccentricity is a piece of the puzzle. But those pieces don't give themselves away (most of them, anyway). You might say the ending of Signs is a tad hokey, but I thought the film was brilliant despite its flaws.
But that's what I think. Do you agree? Disagree? Let me know in the comments.