sorry but i must say this seems inaccurate, natural selection is not neccessarily biased towards anything.
Randomly mutated organisms filter through the non-random seive of natural selection. Those that reproduce simply pass through the sieve. The seive does not appear have a randomness towards any particular individual, as it acts on all the individuals passing through it, one by one, individually...... It is the individuals that randomly can or cannot pass through it. If anything , I would suggest that natural selection (the ultimate sieve of life!) has to be non-random, otherwise organised complexity would probably unlikely to arise, at all possibly.
There may be a "philosophy of science", but philosophy is not a science............and genetic drift is not from a pressure that natural selection applies.
It's surely the result of non-random selective process that results in indidvuals carrying traits that ensured their survival. The individuals that were not so equipped were also non-randomly removed from the gene pool.
Welcome, biomorph. (I assume you're a fan of The Blind Watchmaker, but that's just an inference from your chosen moniker. FWIW, I do make mead, but haven't lately.)
Since you haven't read the last 24 pages, I'll give a brief summary. (For your sake, I hope you haven't read them.) Also, since I don't know your background, I'm going to include a brief mathematics (actually vocabulary) lesson. This may be totally redundant to you. If so, I apologize. First, the math.
If you ever take a college level course in probability, you will learn (or have learned) a very specific definition of "random". A random variable is one whose value is described by a probability density function. A probability density function is a function which is everywhere greater than equal to 0, and whose integral over all values is 1. There's a corresponding definition for discrete systems.
That's a fancy way of saying that the probability density function gives the probability that a variable will take on a given value (for discrete systems) or be found within a given interval (for continuous systems). There's also something called a probability distribution function. That's the integral (or sum for discrete systems) of the density function. The probability that a variable will have a value <= X is given by F(X), where X is the probability distribution function of X.
If something can be described by a probability density function, it's random. By definition. That's not the only definition of random, but it's the one I learned in math class. A random process is one whose mathematical model includes random variables.
Over in another thread, I was giving my review of "The God Delusion", and I noted that Dawkins was absolutely adamant that evolution is not random and that it does not create things "by chance". I objected, saying that many things about evolution, indeed everything about evolution, could be described by probability density functions and that we were, in fact, here by chance, and that Dawkins shouldn't object.
Someone found that a worthy topic of discussion, and started a thread about it. In that thread, mijo hinted that he might agree with my viewpoint, at which point a knucklehead reached the conclusion that mijo didn't understand science. A brief conversation ensued, and then mijo started this thread.
Mijo's basic stance has been, right from the beginning, and completely unwavering, that almost every interesting aspect of evolution could be described by probability distribution functions, it was, by definition, random. Q.E.D. Evolution is random. (Mijo has changed terms to "stochastic", which is a synonym for random, but less confusing, because it is only synonymous with one of the many definitions of random, which is the one that I learned in math class. He hasn't changed his position, just the term used.)
In case you doubt that, let's go back to your sieve. Is it a perfect seive? I think not. I think the holes in the seive are varying sizes. By that, I mean that one organism might be selected (i.e. not killed before breeding) while an identical one, or even a less fit one, might breed. Certain traits in an organism might make it more likely to pass on its genes, but it is impossible to examine the traits of an organism and say that it will or will not pass on its genes. Your seive will let some organisms of one "size" through while blocking others. Indeed, I would challenge anyone to come up with a mathematical model of anything significant in evolutionary theory that did not include random variables. If you can find one, I'll guarantee you that it would be improved, though the math might be more difficult, by inclusion of such variables.
It's really as simple as that, or it could be, but if it were that simple we would have stopped on page 2. What makes it more complicated?
Well, for one thing, there's considerable debate over the usefulness of the description of evolution as a random process. Yes, it is a random process, but does that help us learn anything about it? I think it could, but it depends on exactly what aspect you are studying. Certainly, if giving a top level overview of the process to introductory students, you wouldn't want to emphasize it. If, on the other hand, you are predicting the distribution of allele frequencies, your answers will be more accurate and complete if you include random variables. This includes in the selection process, because a tree might have a feature that makes it fire resistant, and forest fires don't happen with uniform frequency. Your estimates will be inaccurate if you don't include a stochastic component.
Despite this rather obvious aspect of evolution, it seems some people have very strong feelings about that word when applied to evolution. In particular, some have said that anyone who describes evolution as random is probably a creationist. Why they have such strong feelings, I don't know, although I have made some speculations in the past. This post is already quite long, so I'll end it here with one final comment. The feelings that other people have about this word are just that. They are feelings. Emotional reactions. At least, that's my opinion.