Probability of Life Arising Calculations

(edited # 1)
A number of people make the claim that life could not have arisen by chance because the probability of it is too low. It is taken as being so low that even with a few hundred million years and a large fraction of the Earth to work with it still remains a highly unlikely event.
Here re example of a couple of statments made by someone who thinks that is the case:Mike the Wiz writes:It's basically a big big number, - since there was no pre-biotic evidence or pre-biotic conditions anyway - abiogenesis is now a no-go, they try and look to Mars - but that's unlikely even with science, because the atmosphere was too dry - no water could exist long enough - so now they look to Europa, and invoke multiple-universe theories.andMike writes:
The fact is that Math says that the probability of life coming about by chance is highly improbableMessage 185 (Thread Who can be saved? A Christian perspective in Forum Faith and Belief)This is the thread where Mike will show the calculations of this probability. Or perhaps others will want to jump in.I will kick the thread off by giving what I think is the actual, defensible answer to the question:There are too many unknowns to calculate a meaningful probability of life arising on Earth through natural means.There are many other tacks to take while discussing this topic and I think they are all fair:
1)Earth is only one of many worlds. It is highly improbable but there were a few billion worlds to try on.
2)Chemists interested in the topic already understand that a fully modern bacteria could not be the first life form partially because of the probability argument.
3)We don't know how many different paths to complex life are possible. Without that we can't calculate the probability of any one arising.(Whole topic restarted to get Author right)

The intention here is to discuss the probability of life arising given the conditions on Earth, both past and present.If we wander off into the fine tuning of the universe we will end up all over the map (universe actually ).(there is a suggestion for another topic though -- the fine tuning question has been discussed before, you could go there or open another one). Life and Fine-tuning of the universe.

The issue was abiogenesis. Not the orgination of the universe, sun or earth in the place.Have a look at your statments in the OP. You talk about "life".As noted we don't know enough to calculate the probabilities involved. When you go off into discussing the various physical "constants" of our unverse we know even less of what is necessary to do calculations.Your sight suggests that each of these parameters is fine tuned. Please take all of that to the fine tuning of the universe thread.
Life and Fine-tuning of the universe.While I agree all of these things to into any final calculation, if we don't restrict the topic here and divide the whole discusion up it will get very confused.Now, given that the earth exists, where it exists with a sun like ours: how do you calculate the probability of life arising?If you want to separately calculate the chance that earth exists given a universe like we have that would be a separate thread.If you want to talk about the probability of a universe like ours existing that belongs in the above referenced thread.Does this seem a reasonable division to you?If you want the "earth existing" thread and have a phobia about starting threads then ask and I will create one.Once we arrive at probabilities for all 3 issues then we perform the suitable arithemetic on them to come up with the final probability.

Exactly! We simply don't know enough to be able to arrive at any conclusion in this area.To suggest this has anything to do with the existance of a god or other intelligent designer is simply yet another case of god of the gaps.We have to leave some of these questions open as "I don't knows". To suggest otherwise is, well, unwise.