The natural tendency of the mind when looking at a chessboard, as elsewhere, is to jabber away with tangled thoughts. Effective chess requires a different style of thinking: systematic, thorough, and aggressive. You want to ask the right questions before you decide what to do. There are, first, general questions that must be considered routinely. As the great Australian chess writer Cecil Purdy suggested, the most basic are “what does he threaten?” and “what is his reply if I make this move?” Also, and relatedly, “if I do this, will I leave anything unprotected?” and “does he have any checks that can cause me trouble?” There is no need to blunder away a piece by leaving it unguarded if you are careful to interrogate the board this way as a matter of course.
The principles laid out in this chapter might likewise be summarized into a sort of checklist. The goal of studying patterns is to internalize all this and think with your eyes, rather than in a verbal flow chart, but as you are getting started it helps to dwell on the questions that are helpful to ask yourself, with or without words, before deciding what move to make.
With respect to knight forks, the important questions generally arise when you have a knight in the same vicinity as some of your opponent’s pieces, and especially within striking range of his king. Again, the order in which the questions are asked is not particularly important, and will depend on the salient features of the position that suggest themselves to your eye; nevertheless, the ones most often important are these:
Do I have a potential fork? If so,
Is the square that I need protected? If so,
Is the protecting piece constrained? Is it pinned, can it be pinned, or would it be pinned after the sequence of moves I am considering? Can the protecting piece be captured, and then be replaced with a piece that is less effective? Can I capture something that the protecting piece guards, thus luring it away from the forking square? If there is no immediate way to do this, are there any sequences of exchanges that would have this effect?
Can one of the pieces in the fork be captured and thus exchanged for a more suitable target?
If I go ahead and deliver the fork and let my knight be captured, what then becomes possible? What lines are opened, and what pins created? What checks could I then administer, and with what replies? Then what checks or forks would I have?
If I don’t have a potential fork, can my knight check the king? If so, can a valuable enemy piece be moved onto a square that would be forked by my check? If my knight can't give check, what checks with other pieces now are available to me? What are the responses required by each of them? What checks could I then add, and with what responses? Do the positions resulting from any of these sequences create chances for knight forks?
Let this chapter change the way you think about checks and captures. Very often they are usefully given not for their own sake but because they require responses that change the board and may then create good opportunities for double attacks or other tactical strikes. So when you imagine making a capture, do not just ask whether your opponent can recapture and write off the idea if he can. Imagine what would be possible after your opponent recaptures that might not have been possible before. By the same token a check that easily can be evaded hardly is worthless for that reason; the point of a check commonly is to force the king to move or to force other responses that eventually might make a fork or other tactic possible. This basic principle—viewing checks and captures as ways of changing the look of the board to create other opportunities, rather than as ends in themselves—is the essence of tactical thinking.