Abortion!

Feeling awkward yet?

Let's denote for a moment, rather than connote. I'm fairly certain that everybody is pro-life, generally speaking. I'm also certain that we're all pro-choice, in a broad sense of the term.
The reason that people of all stripes use these phrases in dialog to describe themselves, is that the phrases position them into moral favour by very definition: "Well, I'm pro choice, so anyone who disagrees with my stance on abortion is anti choice." Or, conversely, "I'm pro life, meaning that my naysayers must be anti life."

And thus the trick has been played. According to the very terms of the debate I must either be anti life, or anti-choice! How can such a framing possibly end well? Perhaps it is the language itself that prevents consensus.

Apply this to other words, and consider the ways they are often appropriated from their formerly amoral denotations and used as 'attack words.'

'Progress'

'Traditional'

'Backward'

'Duty'

'Patriotic'

'Values'

'Free' (think free market, freedom, free trade, etc.)