Polygamy should be legal.

This is because Employer A and Employer B are usually not aware of one another, nor does their business affect one another. This is not true in a polygamous marriage where the income and doings of all spouses plays a role in their overall taxings and marriage advantages.
1 supporter.

Polygamy should be legal.

An entire new set of tax laws needs to made for "n marriages" where n is the number of people in the marriage. Tax laws as is are not simple by any means, and introducing n marriage laws would be a hefty task.

Facebook is unlikely to be overtaken by another fully featured social media service for the forseeable future.

Facebook, while becoming less "cool", is so integrated into many societies that it has become more of a utility, to the point that not having one is on the level of not having a key device, such as a smart phone. In order for it to die out, many of the current users would need to die, or move enmass
1 supporter.

It is important to fund manned space flight

This assumes we have one "money" that we can only spend on one thing, when in reality funding can go to many separate things. Funding space exploration and funding the end of poverty are not mutually exclusive
2 supporter.

Same sex marriage should be legalized

It's the fact in of itself that homosexuality is present in other species that might make it "normal." It is well known that homosexuals are the minority, however for something to be normal does not necessarily mean it is the most occurring. This of course begs the question of what defines "normal."