Over the last 50 years, ecological experiments under field conditions have exploded in number, type and scope. They remain complex because of intrinsic variability in ecological measures from place to place and time to time, requiring care in their design and implementation. An experiment and its design can only be sensibly considered after thought and knowledge are used to make clear the logical basis for doing the experiment, so that its results can be interpreted in a robust and reliable manner. There are different approaches to any sequence of components of an experiment. Here, a falsificationist methodology is considered, which relates observations (things we know) to models (what we think explain the observations) to hypotheses (predictions about what will happen under novel circumstances if the model(s) is (are) correct). Experiments are then designed to create the novel circumstances in order to test the predictions. How an explicit framework influences the design of experiments is discussed, including the nature of replication and of controls for artefacts. Improving the match between natural historical and ecological knowledge and the interpretation of results of experiments will always help advance the discipline of ecology.