Is an interest in the Philosophy of Biology a good reason to pursue grad studies in Evolutionary Biology? I have always leaned more towards questions surrounding psychology, sociology, and philosophy but fate has me graduating with a BSc in Biology this year. Would it be smart to pursue it further more for the aesthetic beauty I find in its ability to shed light on questions beyond itself than for the science purely in itself?
My understanding is that taught MSc in evolutionary biology will likely differ in course content from university to university. So whether its a good idea / is going to interest you is hard to predict. 

Secondly, what would be looking to do after the masters? That's another way to frame whether masters study is a good choice.