knee jerk reaction

knee jerk reaction 

idiom.  reacting according to a certain habit, without careful consideration

"It is important that we are not drawn into knee jerk reactions to the tragedy in Paris. Any action taken must be carefully considered and states cannot act rashly and alone."

"The knee jerk reaction of many of us upon seeing an obese person is we believe that person lacks self-control. It's more complicated."

"The knee jerk reaction to the release of Amazon's  Echo, a connected speaker with voice command integration, is -- why would I want an Amazon controlled listening device."