"On the other hand I don't think it is out of line to suggest that some or even much of astrology is deterministic."
I agree with this, and you are right--if one thinks about it there are all kinds of "determinisms" in life. The country, culture, religion and economic circumstances one is born to, the educational opportunities, one's physical beauty (yes, it is an advantage in most places) and yes, the emotional health or lack of in ones family and culture all have a determining effect on the trajectory of a life. Every astrologer, regardless of the techniques or philosophical perspective, always engages with the native's biography and in doing so implicitly acknowledges "cause" which is a form of determinism.
So, I think that the whole determinism argument is red herring and distracts from the "real" point of Perry's (and Tarnas's) "arguments" which is that their techniques are better. And since they haven't or won't actually study (and test!) with an open mind the techniques they are attacking, they must resort to pseudo-intellectual arguments in an attempt to discredit the "other guy's" astrology. ie: "pretending that those who employ traditional technique's in their astrology are hopeless fatalists (which is outrageous, because if didn't believe that fate could be negotiated with to some extent at least, why would they bother with Horary or electional astrology). On his website Perry writes:
Since I believe the Universe has intentions for us, I am not inclined to help my clients control or exploit their fate. I am interested in helping them learn from it. Accordingly, my ethics prevent me from advising clients on how to take advantage of a transit for personal gain or profit. I don't tell people when they should or should not do things, like get married, start a business, quit a job, get a divorce, or take a vacation. It has been my observation that whatever the individual does or experiences is always consistent with the nature of the transit anyway. What would be the purpose, then, of trying to outsmart such a profoundly intelligent and obviously purposeful cosmos? Is there not a certain hubris when we muddle in such matters?
So, it could be argued that Perry is projecting his own disowned hopeless fatalism onto his clients when he refuses to even make suggestions as to how a client might negotiate with a difficult transit. From my reading of the articles on his website, he seems to be making the argument that it would be unethical for an astrologer to intervene in any way in a client's 'fate." Which from psychological perspective, is beyond weird--because the fact of the matter is that psychologists make "suggestions" ALL the time! Making suggestions regarding personal perspective and practical action which might be taken is part of a psychologist's job! No, they shouldn't "tell" a client what they must do, but it is good psychology to point out, for example, to a hopeless of depressed patient that perhaps she does have some options and to even give some examples. It is the psychologist's job to help a client out of a mental rut and to give them hope. And to remind them of reality (like maybe you should stop hoping your alcoholic spouse will stop drinking, particularly since he has shown that he has no interest in doing so--not easy to hear, but reality, and not so different from a horary judgment that says that if you sue you will loose.) Or that if you have been recently diagnosed with MS, you will have to accept that you might have learn to live with the fact that you can't go mountain climbing anymore, and help them find other ways to find meaning and pleasure in life. I don't see that even traditional astrologers would have a hard time being psychological/deterministic in that sense. Eg: a chart could help illuminate talents etc which might bring as much pleasure as mountain climbing (5th house stuff).
As for Tarnas: I knew he was into astrology from his book "Prometheus the Awakener" which was published before Passion of the Western Mind, which I own and use as a historical reference from time to time. But Cosmos and Psyche is a mess. I forced myself to read the whole damn thing and it was an irritating experience to say the least. Irritating because he has the ability to cloak his ignorance behind his considerable academic knowledge, but if you really know astrology it is clear that he is as myopic and ignorant as Perry is. Which is shocking, since one would think that at least as a historian, he would be particularly interested in the history of astrology--which, sadly, he seems remarkably uncurious about. Because he basically makes the same "point' that Perry does--that it is primitive and unevolved because it is old.