鈥淭hinking is hard.鈥� So says Daniel Dennett at the start of his book Intuition Pumps and Other Tools for Thinking, published this year. As a philosopher, he speaks from experience.
But just as artisans don鈥檛 have to go about their business with their bare hands, so thinkers don鈥檛 have to work unaided. Over the centuries philosophers have invented a range of handy tools to make thinking a bit easier. Some are useful only in very specific circumstances, such as calculus or probability theory. Others are more broadly applicable. Here is a selection of Dennett鈥檚 favourite thinking tools
REDUCTIO AD ABSURDUM
Literally, reduction of an argument to absurdity. The trick here is to take an assertion or conjecture and show that it leads to preposterous or contradictory conclusions. Homeopathy鈥檚 claim that water has a 鈥渕emory鈥� of substances that were once dissolved in it can be challenged in this way by pointing out that tap water has had millions of different substances dissolved in it.
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OCCAM鈥橲 RAZOR
Don鈥檛 invent a complicated explanation for something if a simpler one will do. This is only a rule of thumb but it has proved extremely useful in science, such as when heliocentrism swept away an elaborate system of epicycles to explain the movement of the planets. (Not to be confused with Occam鈥檚 broom, which is the intellectually dishonest trick of ignoring facts that refute your argument in the hope that your audience won鈥檛 notice.)
STURGEON鈥橲 LAW
Named after sci-fi author Ted Sturgeon, who felt that his genre was unfairly maligned by critics. 鈥淭hey say 鈥�90 per cent of it is crud鈥�,鈥� he complained. 鈥淲ell, they鈥檙e right鈥� but 90 per cent of everything is crud.鈥� This is a useful tool when criticising a discipline, school of thought or art form. If you can鈥檛 land a punch on the good 10 per cent, leave it alone.
鈥淪URELY鈥� & RHETORICAL
Whenever you encounter these questions in a text, stop and think. The author usually wants you to skate over them as if the claim is so obvious as to be beyond doubt, or the answer self-evident. The opposite is often the case.
