What is the English word for a person who spends too much time thinking about philosophy and stuff and never actually gets anything done

Four words come to mind. I imagine there are others. The dictionary meanings of these four words differ slightly and are too tedious to repeat here but I suggest that the person may, according to context, be described as: a dreamer (captivated by and engaged in their philosophic notions); a fantasist (erecting fantasies built on their philosophic notions); a visionary (creating philosophic notions not necessarily well-rooted in present realities); or an escapist (actively escaping present day discomforts by choosing to think of philosophical abstracts).

Are you looking for the word luftmensch (MW Word of the Day: August 1, 2019)?

an impractical contemplative person having no definite business or income

They give this example referring to a philosopher:

"People like Luftmenschen, and they've liked them for a long time. The image of Thales, called the world's first philosopher, cannot be proven, but it's comforting to think that intellectuals have their heads in the clouds and stumble into the well before their feet." — Susan Neiman, Einstein for the 21st Century, 2008

If not, take a look at the archived snapshot of all of MW's WotDs and see if you recognize the word.

This will go down like a ton of bricks, but I thought it was a Frenchman.

I’m actually a Francophile, but as a scientist I’d blame their education system.

(Mind you, there are some advanced scientific countries — not France — where half the population don’t even believe in evolution.)