|Fischer-Larsen during their 1971 match|
Andrew Soltis wrote that when it comes to guessing your opponent's next move fifty percent is a good number to shoot for. I assume he was talking about his fellow Grandmasters, but if that's true the figure for the rest of us must be pretty low! So, maybe my method of selecting a move isn't so bad after all. My method is:
We all make mistakes in calculating, but Soltis claims that you CAN learn how to calculate and reduce the number of mistakes. He adds that during portions of the game such as openings, textbook endings and forced combinations you can be reasonably sure of you opponent's move, but again, I assume he was talking about his peers. Most of us average players don't know openings all that well and we miscalculate tactics all the time. And, endings? How many average players know textbook endings or can even explain the opposition or triangulation?!
From what I have run up against on the internet on quite a few occasions, some players don't even know what a tactic is, so they certainly can't calculate them. I am talking about players who play something like Bxf7+ in the first few moves without reason. Apparently they think the “sacrifice” is playing in tactical style and they've heard “tactics win games” but don't realize there's a difference between a sacrifice and just giving away a piece. I like CJS Purdy's advice because it's more accurate. He said always look for a sound tactic (back in the old days we called them "combinations.") before you do anything else.
Once we get trained in tactical motifs, if we ever do, (see Chess Tempo for a complete list) the number of oversights will sharply decline. Even if we get a winning position, wins slip away by either an outright oversight or because of other factors. Even Bobby Fischer wasn't immune to such gremlins as seen in the following game against Bent Larsen.
According to psychologists, one of the most difficult moves to spot is the backward retreat of a well developed piece because we just aren't trained to think that way. In this game a backward move by Larsen ended all of Fischer's attacking chances and all he was left with was a Q-side that was a total wreck.