Scientist should feel free to be advocates, especially when concerning influential ideas and decisions. While scientists should always maintain objectivity when performing experiments or research, this objectivity should not transfer over to their every day lives. Scientists should be active within their community in advocating smart decisions and beliefs based on scientific principle.
Scientists acting as advocates can help support policies that could improve the world. A common topic where scientists are now taking more direct approach is in environmental policy. Environmental scientists are, naturally, more aware of what actions could benefit or hurt both humans and the rest of the environment when it comes to policy decisions. Policy makers often lack scientific background and a proper understanding of many topics and typically have their own, very biased agenda they want to follow. One study found that academic criteria can reduce the amount of advocacy seen in scientists with Meyer et. al. stating that "academic environmental scientist could play a more substantial role in developing sound environmental policies if the criteria for success in academic institutions...recognized the challenged in making science relevant to policy" (2010, p. 305). While science is objective, the people who work in science should support scientific findings and advocate for decisions that take into account these findings.
While scientific advocacy can take negative forms, as long as scientists remain reasonable and open minded in expressing their beliefs and keep advocacy separate from scientific research, the world will benefit from people with strong backgrounds in science being active in policy and policy development.
Judy L Meyer, Peter C Frumhoff, Steven P Hamburg, and Carlos de la Rosa 2010. Above the din but in the fray: environmental scientists as effective advocates. Frontiers in Ecology and the Environment 8: 299–305. http://dx.doi.org/10.1890/090143