While appearing to be similar, this question is asking about two different things. It’s asking a lot to have anyone sum up these concepts from a psychological perspective in about 400 words. But, my guess is, most writers, like me, enjoy a challenge, so let’s give it a go. First, I’d like to distinguish the subjects at hand. When one speaks of free will vs. determinism, one is almost certainly bringing some sort of deity, or outside force into the picture. When one is a fatalist (or a determinist), (s)he believes that everything is set and there is nothing man can do to change it. We’re merely following a script as set forth by some force (God, perhaps?). Those who believe in free will would tell you that we all choose our own paths and, as our choices dictate, we eventually end up where we belong. I believe the overwhelming majority of persons with religion actually fall somewhere in the middle. Yes, they’ll say, God has a plan, but, yes, man also has free will In fact, God gave man a free will, which eventually led to man’s downfall. So, while man is given free will, he’s best served by following God’s chosen path.
Then we have the classic nature vs. nurture problem. This is similar to free will vs. determinism, but either side can be argued from a scientific/rational standpoint, rather than a religious one. Essentially if a person says we are merely a product of nature, (s)he is saying that who we become is a result of our genetic background. While sounding somewhat like a determinist, the person who believes strictly in nature has science on his/her side. Some things can’t be argued about nature. One’s genetics plays a much larger role in one’s physical health than merely choices made, for instance. I don’t know many people who believe strictly in the nature side of the nature/nurture argument. I do know a few people who believe whole-heartedly in the nurture side. These are people who believe that we are all a product of things we observe and learn. To a nurturist, all behavior is learned. A nurturist would be more like a person who believes in free will. In fact, most people who fall on the nurture side of the arguement do believe heavily in free will.
So, what are the psychological perspectives of these two similar, yet noticeably different concepts. First, let’s remember what psychology is and what it isn’t. Psychology is not the study of “the mind.” Psychology is the study of behavior. Why do people do what they do? Largely, the free will/determinism argument would not come into play, when dealing with persons well-versed in psychology. If it did, most would scoff at true determinism, saying that free will is what separates man from lower species. When you get into the nature/nurture argument, however, psychologists can argue this one to death.
There are a few psychologists (very few, I should think) who would agree that all behavior is pre-programmed in us, via genetics. There are more, though not many more, who would tell you that all behavior is learned. I think most people who’ve studied the human condition and behaviors within would say behavior is some sort of combination of nature and nurture. Yes, because of our genetic makeup, we almost certainly have a predisposition for certain behaviors. This does not mean, however, that we are predetermined to engage in these behaviors. We are still also a product of our surroundings and things learned. Unlike the free will/determinist argument, the nature/nurture problem can often have persons with differing views meeting on a sort of agreeable middle ground.
In discussing psychological perspectvies on free will vs. determinism and nature vs. nurture, one must have clearly defined parameters. While free will/determinism apologists may use religion to support their views, those who argue nature/nurture are much more likely to argue using science as a tool. While interesting stuff to argue in the abstract, these kinds of arguments never truly reach a conclusion, because the concepts are so nebulus.