Are you supposed to capitalise the name of your field?

[phonotactless]

This might be a strange question but I just realised I don't know -- in my statement of purpose, am I supposed to be talking about linguistics or Linguistics? I'm pretty sure if it's specific degree programs it's "the Linguistics degree program" but what if I'm just talking about the field in general, like "I am interested in [L/l]inguistics because xyz"?