Final answer:
Paul Watzlawick developed the strategy of using paradox as an intervention, often used in strategic family therapy.
Step-by-step explanation:
The theorist who developed the strategy of using paradox as an intervention was Paul Watzlawick. He was a key member of the Palo Alto group and is best known for his work in family therapy and general communication theory. Watzlawick’s paradoxical interventions often involved instructing clients to intentionally engage in the problematic behavior they wish to stop, which in turn leads to a change in the behavior or the perspective towards it. This type of intervention fits within the broader category of strategic family therapy, where the therapist leads the family toward positive change using carefully planned strategies.