I think the honest answer is best viewed through the teachings of [Karl Popper][1], notably the [Falsifiability Criterion][2], according to which *anything scientific* has to supply a self refuting empirical criteria. That is, in the absence of an empirical way to test the hypothesis -- upon failure of which the theory is refuted -- the theory in question is hereby not falsifiable, hence not scientific.

As presented, this could be an ideal behind scientific making. As such, it may be perceived as a defining characteristic to which science always aspires, doesn't always achieve. As Creationism assumes the existence of god, **it is not falsifiable** (There isn't, by any definition, an empirical test upon failure of which we deny the existence of god) and as such it is being demarcated from the natural sciences.

I disagree that 

> **The practical rebuttal is to block the philosophical lures and give a sociological answer ...**

in an attempt to win the debate over the current state of affairs, as **there is simply no need to give in to such historico-cultural matters in this context of knowledge.** Claims such as *The [incommensurability][3] of Scientific Theories*, whether formulated by Fayerabend or as it was [plagiarized from Polanyi by Kuhn][4] has long been given strong rebuttal themselves -- see [Davidson in here][5] for example.


  [1]: https://en.wikipedia.org/wiki/Karl_Popper#Philosophy_of_science
  [2]: https://en.wikipedia.org/wiki/Falsifiability
  [3]: http://en.wikipedia.org/wiki/Commensurability_(philosophy_of_science)
  [4]: http://en.wikipedia.org/wiki/Thomas_Kuhn#Polanyi.E2.80.93Kuhn_debate
  [5]: http://plato.stanford.edu/entries/davidson/#Third