We can then show that A must not be true by contradiction.

The result is government by default and policy by contradiction.

Another form of impeachment by contradiction has a subtle effect on the order in which the attorneys present their evidence.

Another use of impeachment by contradiction can be explained negatively.

We eliminate each of these by contradiction, leaving equality as the only possibility.

The argument from marginal cases takes the form of a proof by contradiction.

We argue by contradiction: suppose the new problem is easy to solve.

To argue by contradiction, we start assuming that this claim is false.

Proof by contradiction is another case in which we need to reword claims.

But in a proof by contradiction, we assume a claim is false.