Science is usually defined as the study of material things.
Reductive science is the study of material things that add on the assumption that material things can explain everything else in the universe. Simple examples: our search for God is merely a problem with our parents; love is just a chemical in the brain; beauty is merely a pleasurable experience; free will is only an illusion--in reality it is the result of randomly bouncing atoms making decisions for you; the meaning of relationships is only the drive to procreate; and so on...
What happens when someone challenges that reductive conclusions are also reductive? Here John Cleese gives us a look.
Have a look and let me know your insights!