I work in marketing. But as with psychology, is it art or is it science?
Marketing is not about award-winning advertising or sophisticated value propositions or refinement of sales techniques. It is not about "the creation of something original and beautiful", although that should be a required by-product. It is the creation of something effective. And it is only effective if we can measure the results.
A few years I worked with a great character at a nearby client site. Although very creative and nominally a business marketing guru, he was extremely capable of delving into technical detail, for example to verify suspected anomalies in reports. However he was also perfectly aware of the time and effort required to get the precise answers, and the consequent practical necessity of making broad yet inaccurate estimates instead. And he would often justify his approximations with the same phrase: "this is an art not a science".
I completely understand his sentiment. I fight the same questions every single working day. But marketing is not art. It is just that we rarely have sufficient time, resource, skills or commitment to do the required scientific measurement and to properly evaluate its effectiveness. But marketing is science.