There's too much logic in this post.  Thanks for taking the time to present a rational (and obvious) argument to the OP.  This slippery slope argument presented in this thread is so insulting that most couldn't muster a coherent response.  Sadly, I don't think it will be read in full and mostly ignored.  

I will never understand why people put same-sex marriage and pedophilia in the same context.

I'm sorry, but there's nothing wrong with any of the things you mentioned. #4 and #5 need a bit more clarification though. #4 is OK as long as it's between two consenting adults, but otherwise it's not OK (so no parents molesting their kids, please). #5 is OK as an orientation, since what can you do if that ends up being your orientation? As long as you don't act on it, it's OK. Deeds matter, not thoughts.

Also, #3 is about the same level as alcohol. They're both bad but certainly within people's rights in my opinion.

As for the questions:

1. Polygamy will get legalized sooner or later, and so will marijuana. Prostitution is a tougher question and I imagine it could go either way, even periodically. Incest isn't likely to ever gather much attention so it's probably not going to get legalized in a long time. Pedophilia itself is probably not illegal even now, but molesting children is. Pedophilia isn't going to become illegal and molesting children isn't going to be legal, so everything's going OK there.

2. We're heading in the right direction, just too slowly. Anything that's not clearly harmful should be legal. The less restrictions the better.

It's a cheap and underhanded attempt to demonize same-sex marriage. It's hard to argue against same-sex marriage so they drag in pedophilia (which everyone is rightfully opposed to) and make it seem like the two are somehow connected to each other when in fact they aren't linked at all.

There's no such thing as morality. We've called it that because the real issue is more complex and involves several other facets in life, but that is our first try to describe it. Morality is too subjective to have a true univeral definition. It's relative based on a number of factors and is more of a religious or cult connotation.

A combination of dogma and survival instincts (including empathy and sympathy) describe what we call "morality" much more accurately.

For some, they only do what is considered "good" or rather more accurately "acceptable" because other people do it and it's not frowned upon and won't separate you from the herd, out of fear of punishment, ridicule or isolation. For others they are willing to separate themselves regardless if it is acceptable; usually these individuals have become isolated from whatever herd they were from. Very few of them exist though in comparison to the bulk of herds.

I myself have very similar beliefs to most in first world countries of today and I accept them and recognize why I have them and what they are in a more complex fashion.

And of course as a human I accept that because it's beneficial for me and I'm drawn to it. In a scientific and more accurate sense however, that does not mean that because I do things acceptable to all humans around me that are considered "good" it means that morality is involved.

Humans need to empathize in order to survive, because if we don't we won't have help (emotionally or otherwise) available. Certain brain chemicals release more often and in greater quantities when we're connected with other humans who we can empathize wtih. And in most cases, you can't empathize with a human who will kill someone without a second thought or someone who will steal often or a human who has psychotic tendencies.

They are usually isolated from herds anyways.

I hope to somewhere with no morals at all. That'd be fun! For an hour, or so...before becoming extremely awkward. Still fun.

I feel like all of your points outside of point 5. have some merit of legalisation to them. Obviously everything that is legalized needs laws and regulations to prohibit abuse and missuse of the system, but establishing concise rules about these topics can be very beneficial imo.

1. I already said in the Polygamy thread that, as long everybody involved is a consenting adult and has equal rights regardless of gender, race, age, sexual orientation and other factors, it should be completely fine and a recognized form of human unions. Obviously in a polygamist family struckture that involves children living within it, firm and concise child protection laws need to be put in place, to prevent even more messy breakups (because more people are involved) as well as any form of abuse from adults of the group in general. (In some polygamist patriarchal cultures it wasn't uncommon that the main wive would physically and psycologically abuse children of the other wives out of spite/jealousy for example, without the other wives being able to protect their children from her. Arguably thats a bad example because most of the wives in these societys werent exacly consenting to the polygamy anyways, but love is complicated and can turn ugly, so protection and regulation should be in place.)

2. Again, as long as regulating laws according to the farming, quality standarts and controlled distribution only to adults are given, I don't see the problem with it being legal. The Netherlands have not fallen victim to drug corruption of the souls in the ca. 40 years marijuana has been (semi) legal over there and neither will the rest of the world. Distribution to you teenagers should be prohibited though, since recent studys have shown it to cause irreversible alterrations of the brain, if consumed at such a young age.

3. is legal in my country. Has been for ages. And here comes the tricky part, it doesn't really work. Like with all other points I'd say if the right laws where in place to protect the adult consenting parties from any kind of abuse it would be fine. And in my country a lot of the right laws are in place, but some are missing still, yet theres massive problems with pimps (a concept that should be ruled out by good legal regulation), forced prostitution, underage prostitution, human trafficking, underpayment and horrendus working conditions. This is because the laws that are in place do not get enforced properly and there's not enough laws in place to protect the prostitutes and their customers, not enough laws in place to cut out the middlemen. Prostitution is still stuck in this dirty little corner nobody likes to talk about, it is still highly exploitative work for a lot of men and women, with no proper health standarts in place to protect either the prostitutes or their custumers, but as long as they pay their taxes the states is fine with it. This is NOT how you do legal prostitution.
My impulse is to say there should be an official registration process for every brothel as well as the prostitutes themselves and official licenses and healthcare checks involved. Possibly Unions, work contracts and pricing standarts as well. But most of all it needs to be visible, in a positive light. My fear is that this would only create a clean branch of the industry while all the human trafficking shit forcing young girls and boys into prostitution will just go on it's merry way. That drug addicts would still turn to illegal prostitution to support their habit and someone will take advantage of them. But at least prostitutes and their custumers would have the option of a more clean and regulated avenue in a sort of vote with your wallet kind of way? Obvously the really disgusting shit, like child prostitution must stay illegal and will despite that continue to happen as long as there is a market for it.

4. This is where it gets tricky. For a number of reasons. Again, marrying and having kids with your bloodrelated cousin is not only completely legal, but considered normal in my country. It's not stigmatised in the slightest. Any relation closer than that is prohibited on medical grounds and can not be reconized through marriage, because the close relation could cause severe damage to potential children.

You don't even need to have that close of an incest to see the possible effects of this. There are quite a few instances of cousins marrying among each other and procreating a few generations back in my family. For the last four generations, every generation, at least one family member has shown signs of schizophrenia. We believe that those two instnces are related even though we don't have any real proof, however neither my in my gradparents nor in my parents generation people married their cousins and so far no one in my generation has exibited signs of schizophrenia. Could be coincedence of course.

So the first problem is offspring with birth defects of varying severity.
The other is abuse in form of manipulation and forced ralationships. In case you have grown up with your close relatives, they are going to have some sort of emotional leverage over you. There might be gray areas but I doubt there can ever be true consent where parental incest is involved. The parent you grew up with will always hold an emotional position of respect and power in your live and even children of the most shitty parent mostly want to be loved and appreaciated by them no matter how angry they are at them otherwise. This imbalance of power would create a breeding ground for sexual abuse and abuse of power if parental incest was legal. The same applies to older siblings, but in a much lesser degree.
Consentual incest, even if illegal is not prosecuted unless children are born from the union in my country. In which case usually the male is prosecuted and gets jailtime. It's by far nor the ideal solution and while I don't think sibling couples should have the right to have biological kids maybe they should be given rights to marriage and adoption. Certainly stigmatisation doesn't help them in any way. Parental incest should stay illegal imo as it opens up too many possibilitys for abuse.

5. Pedophilia, if acted upon with a real child or in a way that indirectly meant harm to a real child should always be prohibited. Children can not consent. This goes back to point 4. Adults hold a position of power over the child physically and emotionally as well as possess the cognitive ability for manipulation that especially young children just do not posess. Very few children are able to speak up/defend themselves or get out of an abusive situation on their own accord. Hell very few adults can. I'm all for not underestimating children, but it is a simple fact that, lacking the life expierience of an adult they cannot see the consequences of their actions adequately enough to be able to consent.
That being said, pedophilia might be a simply unchangeble sexual orientation on the spectrum of sexual orientations humans are born with, albeit with the unique variable of being one where the other party can not consent and thus should not be engaged with. As with the other points stigmatisation probably doesn't help, instead we should maybe focus on creating a saftey net of couseling, self-help groups and attentive social cicle. Also as with other sexualities pedophilia in most cases isn't the only sexual orientation these people posess, they might also be attracted to adults, teens or whatever else. In these cases they might be able to lead a completely satisfying sexual and emotional life with a consenting adult partner which would be preferrable. These people have to learn how to live with, but not to act on their sexuality, because your personal freedom ends where anothers well being begins.

Besides all this I just wanted to mention that historically the idea that homosexuality is somehow wrong, is a fairly new one, and has been advocated in the western world only for the about the last 15 hundred years or so. Before that homosexuality was accepted to varying degrees in almost all of the ancient advanced cultures. Although in most of those cultures it was only seen as part of a persons sexual spectrum instead of the categorasations we make today. The ancient greeks had, contraty to popular belief only a very limited acceptance of it, that had to take form of a teacher scholar relationship. The romans were ok with it as long as you weren't a lesbian, mostly because women were not expected to have a sexuality at all. Even the early christianity was fine with it .
The old egyptians were also pretty ok with incest too.

sorry for the monster post, btw

Don't u know 117% of pedophiles are also homosexuals and vice versa?

1-3 should be legalized. Not too sure about 4. 5 definitely should not be legalized.

Well it seems more or less unanimous that people are against pedophilia (outside of the rare "well as long as they don't act on it" semantic argument), but can we all agree that the age of consent should get knocked down a bit in most places?