user-1: Wikipedia page for GM Granda from Peru says:

Julio Granda does not study opening theory. He has said that he has
only read a chess book, the third volume of the General Chess Treaty
of Roberto Grau. Anyway, he admits reading magazines and reviewing the
Informant, which together with his excellent memory and assimilation
capacity, has allowed him to win important tournaments and titles.
Google translation from spanish wikipedia.

Is this possible? Can one become a master without studying theory at all?

user19877: Absolutely, although I do not agree that Julio Granda is a good comparison since it sounds like he has a near-eidetic memory (close to photographic). It sounds like he also absorbs enough that he has, indeed, learned a lot of theory even if not through sitting down and opening books or a computer. I do believe that to get to the IM and GM ranks, you do need to study theory, or you will lose too many games in the opening.
As for becoming a "normal" Master, I am one, who never studied theory. That said, you still need to learn how to play opening pawn structures, and their basic plans. I got to 2298 USCF, and I know incredibly little about theory, but I do understand what I am aiming for in my openings, and what to do should both my opponent and I end up on our own theory-wise.
Lastly, the difference is that there is a huge difference between IM/GM and we mortal "PhishMasters" (fish, aka phish, among masters).

user20712: Anything is possible.  The real question is how likely are you and most people to do it that way.
And it depends on what you call 'theory'.  
I read NO theory. But I read a lot of practical books on openings, tactics, end games, pawn structure, positional play, yada yada.  
They claim that an AI program learned to play Go by playing itself.  I do not know anyone humans that have done that.  We might if we lived millions of years but in reality humans can't do it that way.  Most humans learn by seeing how others,  who win doing it, have done it;  and try to improve on that if possible using the basic tools they learned from practical books.  

-1: <p>Wikipedia page for GM Granda from Peru says:</p>
<blockquote>
<p>Julio Granda does not study opening theory. He has said that he has
only read a chess book, the third volume of the General Chess Treaty
of Roberto Grau. Anyway, he admits reading magazines and reviewing the
Informant, which together with his excellent memory and assimilation
capacity, has allowed him to win important tournaments and titles.</p>
<p>Google translation from <a href="https://es.wikipedia.org/wiki/Julio_Granda" rel="nofollow noreferrer">spanish wikipedia</a>.</p>
</blockquote>
<p>Is this possible? Can one become a master without studying theory at all?</p>
 19877: <p>Absolutely, although I do not agree that Julio Granda is a good comparison since it sounds like he has a near-eidetic memory (close to photographic). It sounds like he also absorbs enough that he has, indeed, learned a lot of theory even if not through sitting down and opening books or a computer. I do believe that to get to the IM and GM ranks, you do need to study theory, or you will lose too many games in the opening.</p>

<p>As for becoming a "normal" Master, I am one, who never studied theory. That said, you still need to learn how to play opening pawn structures, and their basic plans. I got to 2298 USCF, and I know incredibly little about theory, but I do understand what I am aiming for in my openings, and what to do should both my opponent and I end up on our own theory-wise.</p>

<p>Lastly, the difference is that there is a huge difference between IM/GM and we mortal "PhishMasters" (fish, aka phish, among masters).</p>
 20712: <p>Anything is possible.  The real question is how likely are you and most people to do it that way.</p>

<p>And it depends on what you call 'theory'.  </p>

<p>I read NO theory. But I read a lot of practical books on openings, tactics, end games, pawn structure, positional play, yada yada.  </p>

<p>They claim that an AI program learned to play Go by playing itself.  I do not know anyone humans that have done that.  We might if we lived millions of years but in reality humans can't do it that way.  Most humans learn by seeing how others,  who win doing it, have done it;  and try to improve on that if possible using the basic tools they learned from practical books.  </p>
