Their passion for a topic may outweigh their ability to be subjective about it. For example, Al Gore has long been considered an expert on global warming and has incited numerous people to support the adoption of ethanol in the gas supply. Later, when new evidence emerged, he admitted that he was wrong and that ethanol was not a smart idea to support. Experts are only good in their area of ​​expertise. If you call an expert, perhaps a landscaper, to repair your car the results would not be wonderful. In this way the opinions of experts are only important in the areas of knowledge they study and very rarely intersect. Expert opinion in the knowledge areas of arts and ethics is often weaker because "knowledge" in these areas is generally determined by personal emotions rather than reason or language.