etymology - Meaning and origin of "dog whistle" (e.g., Trump's Assassination Dog Whistle)

The recent United States political cycle has been using the term "dog whistle" a lot. From a recent Rolling Stone headline:

Trump's Assassination Dog Whistle Was Even Scarier Than You Think

And their article:

Stated differently: Trump puts out the dog whistle knowing that some dog will hear it, even though he doesn't know which dog.

I assume that the meaning is something similar to double entendre where a statement can be interpreted a few different ways. But why use "dog whistle", specifically? And where did the term first originate?

Answer

It appears to be an expression of the late '80s according to journalist Willian Safire, but its origin and common usage is mainly Australian from the late '90s. The allusion is to sheep-farming where a farmer uses a whistle which is audible only to a dog. By analogy, a specific political message can be registered only by those to whom it is directed:

Dog-whistle politics:

• According to William Safire, the term "dog whistle" in reference to politics may have been derived from its use in the field of opinion polling. Safire quotes Richard Morin, director of polling for The Washington Post, as writing in 1988, "subtle changes in question-wording sometimes produce remarkably different results.... researchers call this the 'Dog Whistle Effect': Respondents hear something in the question that researchers do not", and speculates that campaign workers adapted the phrase from political pollsters.

Dictionary.com dates its origin in the second part of the '90s:

Dog whistle:

• Politics. a political strategy, statement, slogan, etc., that conveys a controversial, secondary message understood only by those who support the message:
  
  
  
  • His criticism of welfare was a dog whistle appealing to racist voters.
  
  
  
  


• Origin of dog whistle 1995/2000

The Taegan Goddard's Political Dictionary defines the expression "dog-whistle politics" as:

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  A type of political speech using code words that appear to mean one thing to the general population but have a different meaning for a targeted part of the audience.

  
  


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  The Economist: “Over the past few weeks, a new expression has entered the Westminster lexicon: dog-whistle politics. It means putting out a message that, like a high-pitched dog-whistle, is only fully audible to those at whom it is directly aimed.”

  
  

According to the following extract from www.macmillandictionary.com/buzzword the expression has Australian origin where it was popular from the late '90s and was exported to the U.K. in 2005:

• The term dog-whistle politics originates from Australian English, and was introduced to the UK by Australian political strategist Lynton Crosby, who was involved in the 2005 Conservative Party election campaign.


• Crosby had helped Australian Prime Minister John Howard to four consecutive election victories, with the focus of the campaigning on so-called dog-whistle issues, an expression in use in Australia since around 1997.


• The dog-whistle analogy was drawn from Australian sheep-farming, where a farmer uses a whistle which is only audible to one dog. This idea was taken over into political contexts as a way of describing a message aimed exclusively at one section of the electorate.