The scientific method is a systematic procedure to acquire knowledge about cause and effect in the phenomenal world.
It is nothing more -- and nothing less -- than formalized common sense. In fact, the scientific method comes so naturally to us, it is so embedded in our daily actions, that we often have difficulties detecting the individual steps.
Figure: The steps of the scientific method. Start at the bottom.
The steps are illustrated by a simple example: It is evening and getting dark outside, and you decide to turn on the light. You walk over to the lamp and turn the light switch ...
1. You make an observation: The light failed to come on.
2. You ask: Why did the light fail to come on?
3. You formulate a hypothesis: The light failed to come on, because the light bulb is burned out.
Cause: The light bulb burned out.
Effect: The light failed to come on.
(In fact, several hypotheses may come to your mind: The light failed to come on, because ... the lamp is unplugged, the light bulb is burned out, the lamp is somehow broken, a fuse has melted, there is a power failure in the building, there is a citywide blackout, ...)
4. You make a prediction: If the current light bulb is replaced by a new light bulb, the light will come on.
5. You desing an experiment: You replace the current light bulb with a new light bulb.
6. You collect data: You turn the light switch, and the light comes on.
7. You analyze your data: You turned the light switch, and the light came on.
8: You compare your predictions with your data.
You predicted: If the current light bulb is replaced by a new light bulb, then light will come on. You observed: After the light bulb was replaced, the light came on.
Hypothesis confirmation: You formulated a hypothesis, you made a prediction, you tested your prediction, and your prediction turned out to be correct. Therefore, you must provisionally accept your hypothesis.
(Hypothesis rejection: You formulated a hypothesis, you made a prediction, you tested your prediction, and your prediction turned out to be incorrect. Therefore, you must reject your hypothesis. Therefore, you must formulate a new hypothesis.)
Technically, we do not speak of proving a hypothesis to be true or false. We speak of failing to reject a hypothesis (and provisionally accepting it) or succeeding to reject a hypothesis.
Failing to reject a hypothesis does not mean that a cause for an effect is determined. For example, imagine there was a citywide blackout which was resolved in the time it took you to replace the light bulb. While you failed to reject your hypothesis and must therefore accept it, the true cause for the light failing to come on was the blackout.
Many more experiments may be necessary to confirm the hypothesis. You could replace the new light bulb with the old light bulb and see whether the light still comes on. Or you could try the old light bulb in a different lamp. Or you could thoroughly examine the old light bulb and check whether its Tungsten filament is broken. ...
The knowledge produced by the scientific method is universal in space and time, empirically testable, and replicable. It is also provisional.