Determination is the common-sense idea that our decisions are determined by our motives and deliberations, by our character and values, and by our feelkings and desires. Determination does not mean that strict causal determinism or pre-determinism is true. That would be to commit the Determination Fallacy Philippa Foot in 1957 correctly doubted that the ordinary language meaning of saying our actions are "determined" by motives has the same meaning as strict physical determinism, which assumes a causal law that determines every event in the future of the universe. Foot notes that our normal use of "determined" does not imply universal determinism.
For instance, an action said to be determined by the desires of the man who does it is not necessarily an action for which there is supposed to be a sufficient condition. In saying that it is determined by his desires we may mean merely that he is doing something that he wants to do, or that he is doing it for the sake of something else that he wants. There is nothing in this to suggest determinism. ("Free Will as Involving Determinism," The Philosophical Review, vol LXVI, (1957), p.441)There are many contributing causes involved in the determination of any decision or action. Many of these may be parts of a causal chain. But as long as some of them can be traced back to uncaused causes, they contribute to freedom from determinism. Some of these may in fact go back before the birth of an agent, hereditary causes for example. To the extent that such causes adequately determine an action, we can understand why hard determinists think that the agent has no control over such actions. (Of course if we can opt out of the action at the last moment, we retain a kind of control.)
Other contributing causes may be traceable back to environmental and developmental events, perhaps education, perhaps simply life experiences, that were "character-forming" events. These and hereditary causes would be present in the mind of the agent as fixed habits, with a very high probability of "adequately determining" the agent's actions in many situations.
But other contributing causes of a specific action may have been undetermined up to the very near past, even seconds before an important decision. Most importantly, these will include the free generation of new alternative possibilities during the agent's deliberations.
These alternatives are likely generated from our internal knowledge of practical possibilities based on our past experience. Those that are handed up for consideration may be filtered to some extent by unconscious processes to be "within reason." They may consist of slight variations of past actions we have willed many times in the past.
The evaluation and selection of one of these possibilities by the will is as deterministic and causal a process as anything that a determinist or compatibilist could ask for, consistent with our current knowledge of the physical world.