First of all, dumping all dead carcasses in the woods is completely impractical, and a really, really stupid idea? I mean, you can't trust everything will decompose and the earth will make use of the bodies and all will be all right, it would be incredibly detrimental to not only the health of nature, but it would eventually come back to bite us in the ass due to a spread of disease, growth spurts of swarming bacteria, etc. Goddamn.
And, I don't see why (TheAmazingFlygon) you think any form of respect for the dead is tied to religious reasoning, unless you're just talking about funerals and the like (priest involvement being the extent of religious relation, i guess)!
Anyway,
The title says it all.
Why should we respect a corpse ?
Why should we care about the desires of a person who does not exist anymore ? Why should we honor last wills and such.
Why do we have to sign a donnor card for it to be legal to give our organs when we die? Why are we considered owners of our body after our death? How can someone who no longer exist still have rights ? Or possession?
Why should we care about corpses ? Why do we give burials or cremation ? would it not be more practical to just dump the carcass in the woods or donate it to an University or whatever ?
There is no real "reasoning" to respect anything that is dead and gone from this world, other than it's something that humans alike have come to do over time, and thus it's become tradition. That's as basic of reasoning I can manage. Otherwise, most human beings who knew someone who is deceased likely had an emotional relationship with them, and so their feelings for them live on even while their relationship does not. Respecting the wishes of someone who is deceased is perfectly valid, simply because it's a legal process. They create a will, sign it, get it authenticated/approved/whatever happens so that it "must" be carried out as the person has described. "Why" should we do that? Honestly, can you "practically" imagine a world that just totally disregards the dead and does what they please with their remains? Things would turn absolutely barbaric. People would start cannibalising, since who cares if you're eating your friend's dead grandmother? They tossed her out, so you're free to do what you want! You know, if that's your thing..
Why do we have to sign a donor card for it to be legal to give our organs when we die? Why are we considered owners of our body after our death? How can someone who no longer exist still have rights ? Or possession?
Aside from actually being in ownership of our bodies after death, everything else is basically a legal matter. Donating organs has to be regulated to avoid things like selling kidneys and shit on the black market, or again, just doing whatever the fuck you will with them after death. If you haven't signed off on your organs being harvested for
medical reasons after your death, then no one has a right to them. Yes, you're dead, but it doesn't give any one living person a higher authority on saying what happens to your body, unless you have signed agreements for yourself, post-life. Everything to do with rights and possession comes down to legal issues, and what you've signed of yourself away after death, and what you have not. Things you have purchased in your name will either be passed on to whomever you've selected to be a recipient or simply tossed out if no otherwise request has been recorded.
I know your question is probably begging to delve "deeper" into the situation, but it's nothing you can simply answer with opinion or fact. Respecting and honoring the dead has been something started aaages ago, ever since someone has first felt the sting of sadness from lost loved ones. Many people die every day that will forever be loved and missed, and those people choose to respect them in their deaths as much as they did in life because although they may not be of this world anymore, the fact that they once were is reason enough.