A straw man (sometimes written as strawman) is a form of argument that tries to create the impression of having the impression of refuting an argument, whereas the real subject of the argument was not addressed or refuted, but instead replaced with a false one. One who engages in this fallacy is said to be attacking a straw man.
The typical straw man argument creates the illusion of having completely refuted or defeated an opponent’s proposition through the covert, hidden, undeclared, replacement of it with a different proposition instead of the actual proposition.
And why would one do that? It’s because the original argument is valid and the person does not have the means to refute it. So he or she hopes to blind observers or the opponent by coming up with a straw man argument that thereby seeks to hide the truth that he or she cannot counter the original argument. That is the only purpose of a straw man argument.
A stalking horse is a figure used to test a concept or mount a challenge on behalf of an anonymous third party. If the idea proves viable or popular, the anonymous figure can then declare its interest and advance the concept with little risk of failure. If the concept fails, the anonymous party will not be tainted by association with the failed concept and can either drop the idea completely or bide its time and wait until a better moment for launching an attack.