I dont know that I accept this definition of life, but it's not the heart of the disagreement (it's a further, probably unarguable disagreement).

I dont understand this. If you think life is just self-replicating structures at a certain level of complexity and that complexity will inevitably increase over time, why do you balk at saying all self-replicators will become life?

BTW here's a well written about the pitfalls of chezlaw brand optimism and certainty as it relates to abiogenesis. History shows an abundance of scientists and philosophers making fools of themselves on the issue. The quotes in the first few paragraph are an interesting read.

http://www.genesispark.org/genpark/spongen/spongen.htm

Ironically it's at a creationist site.

because there's a limited amount of time and extinctions occur. If suitable conditions existed forever then even with Phils low probability barrier he would expect life to emerge eventually.

Its not ironic (or even unsuprising) that your breed of determined incredulity is supported by a creationist site.

The points I make are straighforward and not particularly optimistic. There's a huge difference between understanding why life is nothing special and suggesting we can solve everything in the next few years.

The only bit that could be fairly described as optimistic is that there's a good chance we will find direct evidence of life in the next 50 years but even that's mild comapred to saying we will have it in the lab next Tuesday.

You still really need to address the issue of why you insist your pessimistically low probability barrier is to be taken seriously when faced with some evidence that complecity does tend to increase in the required regions and the condition are common. When a bit more evidence appears do you reduce the likelyhood of your low probability barrier or does it remain firmly fixed in your mind until we're shaking hands?

Excellent questions. I recommend the following article:

http://faculty.kgi.edu/adami/BE2002.pdf

Think of it like the bankroll of a +ev poker player. The bankroll tends to increase over time but there are many setbacks and busto is always possible.

so that doesn't mean all such poker players would acheive a given level however if we have lots of evidence that there are lots of +ev players and that the games last for a long tme compared to the wealth they need to reach then we can be very confident that some will reach that level of wealth. My mild claim is that the modest wealth level of microbe is reasonably likely to be achievable and the phenomenal wealth of the gorilla is less likely.

Who is claiming is a low probability barrier? I'm saying we have no idea, even ballpark, and the absence of that we can't claim anything about the probability. I don't know whether you naturally lack caution or were swept off your feet by the math, but you need to realize that the evidence for your assertions that life is probable is lacking. I read through an article outlining Kaufmann's work of autocatalytic set theory, and while it's a good framework for understanding natural increases in complexity, it doesn't solve the core problem of a total lack of evidence. And I'm not at all convinced that's the theory is solid when applied to life. For example, his simplistic simulations don't consider inhibitors, which is majorly lol. OF COURSE his simplistic simulations are going to show increasing complexity if you completely ignore the factors that could bring it to a halt or slow it down by large orders of magnitude. His work isn't then based on physics, but on a very crude mathematical algorithm where a heap of stuff is assumed. Whether it scales to the problem of life remains to be seen.

http://www.stanford.edu/class/symbsys205/Kauffman.htm

I'll leave the last word to the guy who wrote the talk origins FAQ on abiogenesis, himself a professional scientist and staunch naturalist:

http://www.talkorigins.org/faqs/abioprob/abioprob.html
All I am claiming is what this guy has said. It seems blindingly obvious that the unknowns are far too large to even ballpark it - and won't be solved until the difficult questions of chemistry are answered. So where is your certainty coming from? I'm going to need more than vague references to "look at the literature".

You are. We know its possible and we know evolution is going on at all levels so your only defense is its a massive fluke on earth and the probability of it happening elsewhere may be too low even to come up with microbes with such a vast amount of time and space.

Your insistance not being able to make any claims is silly. If we discovered there were > googlezillion earth like planets would that make life more likely? or are you really stuck waiting for the handshake (sorry for the repeat of this figurative question, seems worth asking again).

I for one welcome a 'handshake' with our new overlords.