I have been attending a biophilosophy seminar this year, in which the topic of "determinism" has often come up. As I understand it the very notion is both complex and the source of much debate.
Certainly "linear string mechanical" determinism is being questioned by workers in nearly all fields. To take a simple example, the effects of a single "cause" (antecedent) can be modulated as a function of other "causes". The distinction between "multideterminism" and "non-determinism" seems to go beyond any direct information we can attain, and thus is good material for the philosophers to debate.
There are the ideas of "a-causality", such as Jung's views on synchronicity. Many in physics have developed somewhat similar ideas.
Then there is COMPLEXITY THEORY and CHAOS. By chance (I think!) I was talking with a student yesterday about events that seem random on the surface but then subcumb to underlying rules. Think of the string of letters in this note.
The whole idea of cause itself remains open to debate. Many years ago David Hume demolished simple ideas of cause as observed. In essence his argument was that all causal statements are inferences. They go beyond the data.
Then, finally, there is the debate over what "random" means. Is random just a very complex pattern? Most say no; others, such as the late David Bohm (theoretical physics), say perhaps yes. Once again the problem goes beyond our ability to observe directly. The result is debate. It has proven difficult to put constraints on this debate (that are not in themselves debatable, at least!).
So where does this leave evolutionary psychology? My own bias goes something like this:
a) We have a biological history (evolution). b) This evolutionary history sets the foundations for our individual development, and thus lives. c) Development itself goes beyond simple genetic "determinism", in the sense that the roles played by genes cannot be extracated from experiences throughout life. d) In us (people) selection seems to have favored a remarkable ability to remold our ontogeny (development) via experience. e) Experience includes essentially everything from cultural constraints through accidental events that we all experience. f) This experience works in part by adding new information, in part by selecting among alternative developmental pathways (by turning on and turning off genes), and in part by maintaining foundations of behavior that might degenerate without support (rather like losing the strength in an unused muscle).
So we have an incredibly complex network in human life. No single event is THE cause, except in the most trivial sense. Multiple events influence the course of future states. Evolutionary roots are essential influences, but these may be buffered to varying degrees under different developmental conditions. At this point we reach the edge of current knowledge.
Thus I very much approve of the issues Mary Beth raises (and that bill raises). We can respect our genes, and genetic heritage, and also respect those other multiple events that help mold our lives. In doing so, we must avoid seeing the fully formed human as "contained within" a gene, or set of genes. That type of logic was tried by early embryologists (little man in the head of the sperm). Its called "predeterminism" which, in my view, is the concept of determinism gone bad (or at least silly, unrealistic, etc.).
I like the stance of "multideterminism" and the concept of "contextualism". Many events, each working in the context of others. Thus no single event CAUSES (in caps) any human action in a direct one to one isolated way. That is why scientists really study little more than DIFFERENCES between populations when variable A or B is manipulated. Genes affect behavior. Experience affects behavior. Genes and experience ALWAYS work together. And so on.
Interesting issues. My last bias is that we need input from any and all who can think creatively/critically about these things. Its not just a matter of FACT; its a matter of interpretation of fact. Interpretation can benefit from the insights of those who start from different points. Insights are themselves the product of multiple factors that we do not understand in detail. And the wheel goes round and round.
The result is not a tidy answer. It is, however, a fascinating puzzle. Who could ask for more?