The question should not be “how likely is it that life develops on a planet based on random processes,” but “knowing that life has developed on earth, how likely is it that it was a product of random processes.” The first question’s answer is a probably a billion to one, but the second question’s answer is much more complicated and much closer to a one to one chance.
The argument is pure BS.
First, there’s a big difference between “evolution” and “origins”. The question here is origins, not evolution.
Second: Any mathematician worth his or her salt will explain quite simply that there is no way to assess the probability of an unknown process.
We simply don’t know how life originated. We can posit models and assess those using probability, but frankly, we don’t even have a model that’s good enough to bother trying to apply math to.
If creationists want to argue that we don’t understand the origins of life, and that we’re just assuming that it happened naturally, we couldn’t argue against it. Neither can they argue for their theory, which is that God did it. The evidence can’t help us choose between the two – at least, not yet.
Third: Morris’s argument is wrong as noted above because he assumes there’s exactly one molecule of at least 100 base pairs that had to come together at one time to start life. If he’s wrong about that, the math is meaningless. Since we have no clear idea how life started, … you finish the sentence.
Fourth: Even if we did have a number, what would it mean?
The Drake equation is NO help here. It only addresses the probability of finding ANOTHER case of life in THIS GALAXY. The universe is much bigger, at least 100 billion times bigger, as far as we can observe. We currently have no answer on whether it’s bigger than what we can see, and if so, how much bigger. It may even be infinite. (The concensus on infinite size seems to change every generation or so, but it’s always a very tentative conclusion.)
If the universe is infinite, than any finite possibility, no matter how small, has a probability of 1 of happening somewhere.
Finally, a probability of zero doesn’t even mean that something is impossible. It just means that you won’t see it happen. However, if you are the RESULT of it happening, and it DOES happen, you WILL see it. Put that in your probability pipe and smoke it!
(Things of probability zero happen all the time. The probability density of a certain electron orbit is zero at the center of an atom. The electron has to move through the center to get from one side to the other, and it does.)
It’s most useful as a retort to “evolution is just a theory.”
The top end of the intelligent design argument continuum blends into the bottom end of speculative cosmology(pdf).
Speaking as a person trained as an anthropologist, with its concomitant core belief in evolution, I think most mathematics is impossible, starting around first-year algebra. And I’ve worked with electricity a lot, but part of me thinks it’s magic. Just means I don’t know enough, not that either is wrong-headed.
Along these lines, I recommend the book “At Home in the Universe” by Stuart Kauffman, even though it’s a decade or two old now. He models complex networks and shows that in networks that are similar to what we think the primordial soup was like, there’s a strong trend toward behavior that is complex but not chaotic. In other words, if his work is realistic, the emergence of life from nonlife is far from improbable or unrealistic. It might have been extremely likely - even inevitable.
Also visit the website of the National Center for Science Education. Take special note about their tips for testifying at school board meetings. After all, some of the people you are conversing with may not be especially interested in the underlying science. Note particular recommendation number 9: Call on the clergy. Pro-evolution clergy are essential to refuting the idea that evolution is incompatible with faith. Voices for Evolution contains useful statements from mainline religious organizations (Catholic, Protestant, Jewish) affirming that evolution is compatible with their theology. If no member of the clergy is available to testify, be sure to have someone do so-** the religious issue must be addressed in order to resolve the controversy successfully. ** Last sentence emphasis added. If you are concerned about persuasion you have to address their issues, not just your own.
Since the OP also mentioned Hoyle: Hoyle’s argument is that it is unlikely that life could have developed so quickly on Earth, and thus that it must have instead developed even more quickly, in an environment less hospitable than Earth. The logic leaves something to be desired.
I cannot recommend Kauffman highly enough.
Not to go off-topic here, but I don’t understand their concluding sentence:
Unless we are now living in a simulation, our descendants will almost certainly never run an ancestor-simulation.
We already run very simplistic ancestor-simulations on computers, including scientists mentioned in this thread who are running models to assess the spontaneous origins of life. On what grounds can they say with certainty that, should we reach post-human status, we wouldn’t run a much more complex simulation?
One point:
“… overwhelming improbability of such a thing coming into existence by chance, simply through the purposeless laws of physics …”
These are two completely different forces (if I may use the term).
I have some sympathy with people who cannot conceive that all evolution from a single celled organism to an elephant could occur just by chance mutations. Given the scale of time most people can actually conceive (or maybe only people like me), it’s not surprising.
However, the “purposeless laws of physics” do dictate that complex molecules are likely to develop in certain ways. If the mechanisms of evolution were better explained, fewer people would doubt them.
Isn’t that a bit judgmental, and expecting that all elements should follow your ethico-religious beliefs?
I would respectfully suggest that people go for clear and accurate over clever, when trying to help people see the fallacies in creationist arguments.
[Disclaimer: I am not a creationist. However, I have sympathy for those who just cannot grasp evolution; I blame the failure on the way it is taught. “So this base pair is swapped out for this base pair, then that happens a lot more, and then we have 24 different species of finches on the Galapagos” is about all the explanation a lot of people get; toss a few legally mandated “… but this is only a theory”'s in, and it’s amazing anyone in the US believes in evolution. This has gotten me in pointless arguments before.]
But, gosh! Every time we find a fossil, it creates two new gaps! We aren’t filling them in; they’re multiplying! 
Another amusing (perhaps?) example of this: it’s relatively easy to calculate that fleas cannot possible “jump” the huge distances – dozens of times their own height – by ordinary muscle power. And this is essentially true. But what fleas actually do is set a little hook into their own tissue, tauten their jumping muscles, and then release the hook.
It’s a bit like a person with a bow and arrow. It is impossible for an archer to “throw” an arrow 100 yards, but if he can store energy in a spring – a bow – he can do it just fine.
I know that’s true, but I’ve never been able to convince my dentist. But, on the subject of tooth decay, I trust her expert judgment, not mine. Most (not all) mathematicians know the limits of their knowledge and expertise.
And the answer to the OP is, of course, no.
Actually, fleas’ jumping ability isn’t particularly more impressive than humans’. Maximum jumping height is basically independent of size, and fleas can jump to about the same height that humans can.
I haven’t read this paper closely, but in related ones that I’ve read, the argument is essentially that if such a simulation were to be possible, then the simulation would have to be detailed enough to allow for the simulation to be run within it, ad infinitum. Since every level of the simulation would be simulating every level below it, probability dictates that we are almost surely not the top level, therefore we a currently living in such a simulation.
On a related note, I’ve seen the argument seriously made that quantum mechanics indicates that we are indeed living in a simulation and that, in addition, our scientific investigations are butting up against the granularity of the simulation.
There are some interesting laws of scale here. JBS Haldane wrote on this in his (lovely) “On Being The Right Size.”
A flea could not “jump” the height it can, but does it by storing energy in stretchable tissue. Again, it’s like asking a person to “throw” an arrow 100 yards.
Humans and fleas “jump” by entirely different physical mechanisms.
[Quote=GIGObuster]
Just realizing that Carbon is the whore of the elements …
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I actually think prostitution should be legal, and I’m an agnostic of the teapot variety. In any case the point stands, Carbon likes to hook up with many in the periodical table, other elements are more noble and do not mix at all with others, they are a gas. 
More seriously the point is that when the element that is more involved with life on earth has that capability it does undermine the idea that “life had a provability of one in a billion billion to start”. The elements conspire against that misleading creationist say so.
That’s okay: the creationists just take a step back and say that the laws of chemistry were intelligently designed by God. Why, if the strong nuclear force were just a tiny fraction stronger, or a tiny fraction weaker, chemistry as we know it could not exist.
It’s a trick that, in the long run, will always work. Why A? Because of B. Why B? Because of C. Why C? Because of D. … Why Z? Well, we don’t know… AHA! That proves that only God could have done it!
(And for some odd reason, it’s always their own religion’s God, never someone else’s…)
As Indiana Jones said about another group of extremists, “I hate these guys.”
And in a similar vein, we have very few skeletons of fossils from the inhabitants of ancient Rome. We must therefore conclude that Rome was severely underpopulated. There are also many missing links in my ancestry - I must not exist.
I like to think of low probability events in terms of the lottery.
It’s incredibly unlikely that Joe Smith in particular wins the lottery. But it’s also incredibly likely that somebody wins the lottery and it might as well be Joe Smith as anybody else.
Likewise, it’s incredibly unlikely that a particular chain of events occurs to produce life as we know it. But it’s incredibly likely that one chain of a family of such chains will occur and it might as well be the one we observe.