A theory of change is simply how you think the change is going to happen. Once you have a clearer idea of how the change might happen, you’ll have a clearer idea of the part you need to play.
An example could be cycle lanes in a town. You want more people to cycle. You suspect that one of the key factors stopping people is that they don’t feel safe cycling. You therefore suggest cycle lanes. In order to get cycle lanes painted on to the road, you need to convince the local authority to spend some money. You could speak to individual councillors, you could ask to present the idea at the next council meeting, you could ask local residents to sign a petition or write letters. Essentially, how is the change from a few people cycling to many people cycling going to happen?
Different aims and different campaigns often require different theories of change.
One theory of change is legislative change. If you support this approach for the issue you are campaigning on, then you would say that getting a change in the law is the most important goal. Let’s speak to politicians or the courts and change the law. This would probably involve small meetings with politicians, detailed briefings to politicians, or possible a legal case in court. It is likely to look like a lot of small steps. In this approach, public opinion would shift after the change in the law was made.
Another theory of change is direct action. If you support this approach, you’d say that those with the decision-making power don’t listen to the public until the public demonstrate how much they care with acts of civil disobedience. Until people are arrested for blocking roads, or chaining themselves to trees, then the story will go unreported and decision-makers will assume (possibly correctly) that only a handful of people care.
Most campaigns borrow from different theories of change. Many campaigns also recognise that other people are doing something different which can complement their efforts. In any given issue, it may be that one group is focusing mainly on legislative change, another is thinking about the media angle, and a third group is organising direct action.
There isn’t a right or a wrong answer. However, campaigns work better when the overall aim (such as encouraging greener transport) and specific goals (such as creating cycle lanes) have been written down and a theory of change considered.