This argument is often brought up, so I’ll offer the short version of the rebuttal. If you name a specific event which has a probability on the order of 10^-150 and then sit around waiting for it to happen, I agree you will never see it. That doesn’t not mean events of this magnitude never happen. They are happening all around us all the time, but no one predicted them, and most are not particularly notable, so they pass unnoticed.
If we apply Dembski’s methods to common occurences, and take into account the entire event history leading up to the occurence, the probability of any event will exceed the “Universal Probability Bound”. It’s just a matter of taking a sufficiently long and detailed history into account until the multiplicative probability is close to zero. If I wished, I could show the impossibility of my having cantaloupe for breakfast this morning this way (but I did!)
I am NOT saying anything about the possibility of life forming naturally. I think most will agree that something unlikely must have occurred. What I am saying is that Dembski makes a bad argument for ID, and bad arguments help no one.
This is not an unreasonable position in itself. I don’t agree, but that’s OK. 