Reductio ad absurdum (Latin: "reduction to the absurd") is a form of argument in which a proposition is disproven by following its implications to a logical but absurd consequence. An example of a reductio ad absurdum would be to note the consequences of an ad coelum theory of property would be that a land owner would have ownership over other planets.
Attempts at making a reductio ad absurdum argument can easily create a straw man fallacy if it distorts the proposition which one is trying to disprove. The example above can very easily lead to a straw man fallacy in that it states that a person cannot own land because no one person has the right to own a planet if other people require the land. The fallacy, thus, lies in the difference between the ability to own land and the right to own land, which are not equivalent.