“Reductionism” is the basic idea of “reducing” an argument or problem to a simpler analogy. So, a “reductive argument” would be the reduction of a complex argument down to an easier set of facts.
Sometimes, this is a genuine attempt to make it easier to understand. However, often, this is the same as a “strawman” argument, which is when I purposely and disingenuously simplify someone’s argument into one that’s easier for me to defeat. This was named for the straw dummies swordsmen would practice their fighting skills with – you can always defeat an opponent made of straw.
I found reference to biology and physics in several definitions. For example, from Merriam-Webster:
explanation of complex life-science processes and phenomena in terms of the laws of physics and chemistry
I found this is more than one place, so there’s apparently some special usage of the term in life sciences.