Well, yes and no.
Any substance can be disadvantageous in large amounts or if used improperly. Water is considered non-toxic, but a glut of water causes flooding, and trying to breathe it may kill you. Even the safest over-the-counter drugs can be deadly if you overdose on them. Carbon dioxide is no different. It is a necessary part of our ecosystem. Animals produce it as a waste product of metabolism, and plants absorb it to use as building material, which is then eaten by animals. Carbon dioxide is necessary and ubiquitous. On the other hand, in large amounts atmospheric carbon dioxide traps heat, not allowing it to radiate into space. Combined with light coming in from the sun warming the Earth’s surface, this produces a greenhouse effect, and is suspected to be the main cause of global warming.
This issue seems to be at the center of a misunderstanding about CO2. Some people, knowing it to be necessary and ubiquitous see the EPA’s activity and the push for cap and trade as politically and financially motivated. To them, it is all corruption. They seem not to understand that in the large amounts produced by power plants, it is a greenhouse gas. These people have received much ridicule for this.
On the other hand, there is a second misunderstanding. Some of the people citing CO2’s necessary and ubiquitous nature (at least among Rush Limbaugh listeners) are only doing so because they are under the impression that the “global warming alarmists” are playing fast and loose with the facts in trying to make us fear CO2, saying it is toxic.
People need to understand that there are two levels that debates happen on. There is the debate between educated people, and the debate among uneducated people. The uneducated tend to get things slightly wrong and in any case are fed wrong information because it is assumed that they will not understand the complex truth. They are fed simple arguments. Because of this, the educated pro-CO2 crowd picks apart the simple arguments of the uneducated anti-CO2 crowd, and the educated anti-CO2 crowd picks apart the simple arguments of the uneducated pro-CO2 crowd. The educated people of both groups never debate each other, and both sides think they have won.
I suspect this phenomenon occurs over a lot of other issues as well.
The cure: when you find someone who clearly doesn’t know what he/she is talking about, don’t assume their beliefs are necessarily wrong. Instead, seek out someone that believes the same thing but can give you better-informed arguments.