It seems to be the materialist/reductionist perspective, which is based on 19th century science (despite being totally outmoded since the early 20th century and

It seems to be the materialist/reductionist perspective, which is based on 19th century science (despite being totally outmoded since the early 20th century and the discovery of emergent properties in physics and biology alike). I sincerely think that it's the thing holding us back the most in the 21st century.