“1. Human beings meet their needs by using the resources in their environment.
2. Human beings have a limited knowledge of their environment.
3. Human beings have the ability to learn and remember so their knowledge of their environment increases over time.
4. As human knowledge of the environment increases, new ways of meeting human needs become available.
5. If the news ways of meeting human needs are better than the old ways of meeting human needs they will be adopted and the old ways discarded.
6. The adoption of new ways of meeting human needs constitutes social and cultural change in itself, but also leads to further social and cultural change.
7. The order of discovery of new means of meeting human needs follows a particular path from that which is most easily discovered to that which is more difficult to discover. Many discoveries require prior discoveries before the discovery can take place. This means there is a necessary order in the discoveries that constitute and cause social and cultural change.
8. The particular order in the discoveries, means social and cultural change occurs in a particular order, so that the sequence of social and cultural change is inevitable and is rationally understandable.

All of the above statements appear to be obviously correct. If they are then the study of social and cultural history can be considered to be a science in the same way as biological evolution is considered to be a science. Social and cultural change derived from increasing human knowledge is not random and so can be scientifically understood. We can not predict the future of social and cultural change as we do not know what future discoveries we will make. This is analogous to biological evolution where changes in living species are unpredictable as we do not know what changes will occur in the environment of those species. However biological evolution does make changes in living species rationally understandable, just as an analysis of the order of discovery of the human environment makes social and cultural change rationally understandable.”