Thank you to everyone for your thoughts, both supportive and opposing! And thank you Isothenia for the link you provided. The book Cooked by Pollan is one of five other sources. I should have clarified that my professor said I can use it as source, but that it won't be considered a philosophical source. I was also informed yesterday that this book combined with another non-philosophy source will only be counted as one source. He is also instructing us not to define the terms of the paper in the beginning of the paper because he thinks it's better to do that as you go. This also frustrates me because it contributes to the idea that he is not giving us the freedom or independence to develop an original paper reflective of our interests, passions, and writing styles. It feels as if we are instead being told to cater to his desires and personal preferences.
Dumnamechange said "My recommendation is to just deflate whatever value you are for some reason attaching to these terms." I do not think I am attaching value to the term.
Dumnamechange also said "Can you really not just accept that he's not a philosopher and incorporate his work in some other way?" Why should I accept it? My professor is not the ultimate guide for determining who is a philosopher and who isn't. Yes, I am going to have to incorporate his work as a non-philosophy source according to my professor, but that doesn't mean I can't question it.
One quote that I really empathized with was from TheQuakerMan, who said:
"If you are doing something philosophical with his work, are writing about a philosophical topic, and you probably are using many other philosophical resources, I don't see why it matters if Pollan is a philosopher or not to be used as a source, especially if it influences your thoughts.
How many philosophers have used literature or other forms of art as influence to start a project, as a source, or as a reference?
If Pollan writes about food, and you are writing a philosophical paper about food, I think whether he is a "philosopher" or not ultimatley does not matter."