That is a simplistic and misleading way of describing Arminianism's hamartiology and soteriology.
There is only a difference in degree between Arminianism and Open Theism. They are clearly fraternal twins but not Siamese Twins. IMO both diminish man's depravity and God's sovereignty in an unsuccesful attempt to rescue God from bad press and to soothe pastoral couseling perplexities.
As long as you are stating that that's your "opinion" of Arminianism, I'm not going to bother debating it.
Arminians who want to retain predictive prophecy and inerrancy stop short of a fully open view of God. Arminian is not Open Theology, but it is Theology Ajar!
You seem to think that predictive prophecy and inerrancy demands causation. Foreknowledge isn't necessity; in other words, just because God knows something will happen doesn't mean that God has caused (at least, actively) it to happen.
Those who are able to remember that God, who in addition to being omniscient is also omnipotent and omnipresent, has the power to bring about anything He determines or PLANS to bring about. I don't have any problem with predictive prophesy, at all.
Look at it this way. Imagine for a moment that God has ZERO foreknowledge but does have PERFECT, ABSOLUTE POWER. He could plan to bring about a thing, he could announce his plan, and he could bring it about by means of his power. His power, being absolute and perfect, could not be thwarted by anything. He could announce his plan hundreds of years ahead of time, and we would see it as prophetic, which it would be. It would certainly come about, but it would come about because of God's power driving it to completion.
Due to our previous discussions on this topic, and my ignorance of it, I purchased and just received Boyd's book, "God of the Possible" from Amazon.com. Initially, I'm most attracted simply to the problem passages that give rise to the "open theist" position (I tend to read back to front or to jump around).
To date, despite reading another's ideas, I find myself still an advocate of simple foreknowledge. Without referencing the book, let me say that Boyd hasn't really tied the ends together for me yet in terms of "WHY" God chooses not to know IF he knows all contingencies. (So far, open theism is striking me as simply a variation of the "God chooses not to look" school of theology.)
He has pointed out some interesting passages that I'd not considered, and that must be taken literally. The one that sticks in my mind the most is God telling Hezekiah that Hezekiah would die. That, clearly, was not an "anthropomorphism."
I mention the passages because I am unsatisfied with the way either calvinism or arminianism has handled these passages. They leave the literal to explain them -- and I am a literalist.