If I had to choose the most popular misconception in chess, I wouldn't hesitate for a second. It is the so-called 'weakness' of doubled pawns. I cannot tell you my dear readers how many times I have encountered the same situation during analysis of my students' games. It usually goes like this:
Me: Why did you play this move?
Student: I was afraid that my opponent would create doubled pawns in my camp.
Me: So, what was wrong with doubled pawns?
Student: (pauses, gives me a surprised look) Well, they are bad for your position, you know...
After having this kind of conversation almost on a daily basis, I started asking my students to show me any position or even just a part of a position where doubled pawns would be bad. As a rule I get a position similar to the next one (please note that we assume that there are many more pieces in all the positions that we discuss today, so this is just a part of the whole position):
After setting up a position like this, I usually get another 'look'. This time it is a mischievous look which says "Told ya, they are bad!"
Then I modify the position a little bit:
Now it is my time to be mischievous. "Please tell me how exactly are these pawns weak?" I ask. And then to help my student understand what's going on I set up the next position:
Now both Black pawns are weak. So, you can see that in the first diagram Black pawns were weak not because they were doubled but because they were isolated. In the second position we 'fixed' the problem and the pawns weren't weak even though they were still doubled. In the third position Black's pawns are very weak precisely because they are isolated even though they are not doubled.
The same way it is easy for me to rebut the other kinds of 'proof' that doubled pawns are bad for your position. For example my student creates the next position claiming that doubled pawns make the position of the White King very weak:
And as a response I set up the next two positions:
Here doubled pawns are actually giving an extra protection to the White King.
In the last position the White King is extremely vulnerable even though White does not have doubled pawns! Again we have the case where the alleged "weakness" of doubled pawns is substituted with something else (in this situation it was the open 'g' file against the White King.
So again I ask my student to set up a position or just a part of a position where the game is ruined because of the doubled pawns and nothing else. After some more fruitless attempts as a rule the student gives up.
Can you my dear readers answer this simple question and show such a position in your comments? Next time we'll see the positions (and games!) where the outcome was decided exclusively by double pawns and by nothing else!