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Backwards Reasoning

Disciplines > Argument > Types of reasoning > Backwards Reasoning

Description | Example | Discussion | See also

Description

Think backwards. Start from what you want and then seek supporting logic.

If you cannot find sufficient reason then you may abandon the decision. Or you may resort to fallacy, particularly when you are more concerned with persuading than being logically correct.

You can also think backwards in time, starting with a desired future and working backwards to

Example

A business leader has already decided what the strategy for the following year will be. He seeks arguments and evidence that will make the strategy seems sensible and ignores anything that would make it seem unsound.

A child is asked why they did not do their homework on time. They start with not doing homework and work backwards to seek an excuse. They come up with the reason that they left their book at school.

When a person in business wants to propose a new product design, they start from it being a success and work backwards to what they must do now to engender that success.

Discussion

The main approach is not so much to be logical, as to appear to be logical. We are not rational but rationalizing. In this way we can feel right even when deep down we know we are wrong.

This is not inevitable and we do have a choice. We can choose reason over unreason, though this Congress at a price (which is perhaps why so many of us take the rationalizing path). To be a reasoning person means thinking before speaking, sometimes rather deeply. This will mean that you speak less, which is probably a good thing.

Reasoning means being sure of basic facts. It also means making logically sound inferences and deductions that avoid the many fallacies that lure waiting to ensnare us. It requires arguments that chain cause and effect rather than making breathtaking leaps of faith.

There is, in fact a way of using backward reasoning that can be helpful. When you are thinking about some thing in the future and want to connect it with the present, it can be better to start with that future event and work back towards the present than to step forwards from now.

One way of using this is in creativity. When you dream up a desirable future, think 'What must happen just before that ideal point?' Then keep asking again 'What must happen just before that?' until you reach the present.

A variant on creative thinking is problem solving where you want to find the best way to implement a rational solution. Again, the 'What must happen just before?' question can lead you to a useful implementation plan.

Another use for backward thinking is in risk management, where you are now looking at an undesirable future. The question note is 'What might happen just before that?'

In fact this stepping back from the future can be used for negative purposes such as lying. If you want to create a credible story, it can be better to start from the present and work backwards than to start from the point of truth and add, Pinnoccio-like, ever-more incredible lies.

Likewise, the original post-rationalizing be constructed more effectively by backwards thinking. After all, while you may desperately want what you say to be the truth, in reality it is a lie.

Backwards thinking is actually a type of cause-and-effect thinking. When you think forwards, you are looking for the effect caused by an event. A problem with this is that there can be many effects and it can be difficult to know which one will lead to the future in question. Thinking backwards is easier as, while effects can still have many causes, the route to the present from a future is often clearer than the route from the present to a future.

See also

Lying