What do you call someone who acts and thinks it is helpful, even though they do not know the context of what is going on?

Question

What is a name for a person who assumes they are doing something helpful, even though they are ignorant to the situation? Someone who reacts without bothering to understand what’s going on, and feels as though they are doing good? Is there such a word?

For instance, someone who pulls another out of the pool, and pats them self on the back for saving them from drowning...without ever asking if the person was drowning or merely swimming.

Answer 1

Capricious and impulsive come to mind.

Citations: For the American Heritage Dictionary definition: capricious. (n.d.) American Heritage® Dictionary of the English Language, Fifth Edition. (2011). Retrieved June 11 2018 from https://www.thefreedictionary.com/capricious

For Collins English Dictionary: impulsive. (n.d.) Collins English Dictionary – Complete and Unabridged, 12th Edition 2014. (1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014). Retrieved June 11 2018 from https://www.thefreedictionary.com/impulsive

Answer 2

Officious is a good word for someone who proffers unwanted or unsolicited advice.

Presumptuous is a good word for someone who assumes things without actually understanding the situation.