A helpful tool of argument used to save time or energy or something when encountering ideas new or old (or even ideas that you think you've probably heard before anyway). By grouping someone's argument or entire viewpoint with a commonly known philosophical term, and following with an immediate derogatory comment you can sometimes silence your opponent, sway passive spectators, or, at the very least, prevent yourself from thinking about it.

Useful combinations:

liberal hogwash
blind conservativism
New Age bullshit
typical sophistry
post-modernist crap (or, for better results "po-mo")
commie drivel

Some helpful, throw-away phrases include:

What a bunch of...

You're/That's just full of...

That would make sense, to a... (personalize it for this one)

Some claim that alliteration is also a good aid for dismissive comments (e.g. conservative clap-trap!. Another hepful tip is to remember not to introduce new information that might incite further discussion. It is a gamble whether a phrase like "pre-Socratic tautology" will shut everyone up or simply create inquiries as to what you mean.

Categorization can have similar effects on conversations as dismission, but using the former allows your hostility to remain latent, and what's the fun of that?