How you know a conversation has lost scientific credibility

Conversations pertaining to science oftentimes transforms into meaningless debate on personal positions and emotional issues.  The parrot-effect of media, where people who watch TV shows and repeat what a host says as fact, is a toxic influence.  There are some simple ways to derail this effect that has arisen in recent interviews that should really be emphasized and explained to people...

1. The need for a nullifying criterion that you establish in advance to clearly define what observations or information you would need to reject or negate your perceptions.  This is grossly absent in the media.  Not many self-proclaimed experts understand that you must set a clear set of criteria that can effectively change your position on a matter.  In the absence of a nullifying criteria, the conversation is no longer scientific, it is ideological.  When you encounter someone who seems committed to a particular set of ideas, ask them the simple question of "What would change your mind?"  If they have no null hypothesis, then don't waste your breath.
2. Cherry-picking of information to suit the needs of arguing parties.  An inability to agree on facts is pretty consistent with this practice.  "My facts are true, your facts are not."  This is an argument strategy that attacks the observer and not their observations.  When you encounter someone who cherry-picks information, it would be useful to clarify before moving forward why they hold these observations to be true in spite of other observations that are available.  What makes these set of facts or observations more valid than the dozen of other studies that say otherwise?  The burden of proof is on the observer to prove that their ideas are more significant or are more valid than others.  In the absence of this proof, their position should really not be validated.  This is very much like the debate between Bill Nye and Ken Ham.  There's an abundance of evidence to support the model of evolution by natural selection, while there is an absence of evidence to support the other.
3. Pointing to history or anecdotal examples.  This is the most aggravating to deal with.  Many people will often point to the past in an attempt to validate future or current behaviors.  The only way that this approach holds true is if there is a rationale and if they have a criterion to negate their current position.  If a person's point-of-view has no other rationale, other than history or anecdotal evidence, to influence their perception, then you must question how they would ever negate the adherence to their decision.  It's the equivalence of stating that one observation is enough to apply it to all future observations...
4. Inability to invalidate studies.  One thing that bothers me is when people will speak out against known studies and they either play dumb or fail to invalidate the studies presented.  The CDC, FDA, the NIH, the international agencies that produce these studies are responsible for these studies, not congressmen.  When people go on television and claim that these agencies are bogus have the burden of responsibility to generate the necessary evidence to substantiate their position.  In the absence of their evidence (as convenient as it is to leave them at home), their argument collapses.
5. Inability to clarify their own point.  The absence of depth is damning in this case.  If a position is to be taken, it must be thoroughly investigated in multiple dimensions.  To simply impose a narrow view in the absence of neighboring and relevant context only illustrates how shallow the position really is.

The following YouTube clip (removed since the account was "terminated") emphasizes the clear distinction between people who conduct actual research and people who simply spread propaganda.  Can you spot the difference?  Who is the one who has done their research and who is the parrot who claims that research suggests otherwise?

Since the YouTube account was terminated, I'll summarize it's contents.  A former congressman was arguing with a news anchor about the claims made that the MMR vaccination is tied to autism.  And despite the news anchor's inquiries about the legitimacy of their findings, the former congressman held his ground, but not for scientific reasons.
 
In the clip, it was quite clear who had done their basic research and who had simply looked up on Google, "Anti-Vaccination Arguments."