What makes someone a professional scientist? asks a series of posts at T. Ryan Gregory's blog. The set was spurred by him defining a professional scientist in an aside on a related post "as someone who does scientific research for a living, publishes research in peer-reviewed journals, and is funded by granting agencies to do it." A comment from B Harpur wondered, then, if graduate students would count as professionals. Gregory says no. "Graduate students are critical to the scientific endeavour. But they are still in training and hopefully are aware that they have a lot to learn before they can head out on their own," Gregory writes in this post.
In addition, Gregory says that not even all science professors are professional scientists, particularly if their focus has become more on writing or teaching. In the comments section, Larry Moran says that Gregory wouldn't consider him a professional scientist and notes that many scientists are losing their funding. "When do they stop calling themselves professional scientists?" Moran asks. Gregory responds that grants aren't the only criteria and that there is a difference between seeking funding for projects to continue to do research and not.