Today I would like to briefly consider the question of whether the cosmic bringing forth of humans was inevitable. This question, when fully elucidated, clearly has an answer (either yes or no); however, it is questionable whether humans can know with certainty what the answer is. Let us elucidate the question. There are two elements to the question. Firstly, what is a 'human'? Secondly, what does it mean to talk of 'inevitability'?
Let me start by considering the notion of 'inevitability'. According to conventional wisdom the cosmic bringing forth of humans was not 'inevitable' because the paths which biological evolution takes are not 'directed' towards a particular outcome. According to this view, biological evolution is simply a process through which the 'fittest' life-forms survive. If one believes this then it is hard to also believe that one particular life-form - the 'human' was 'inevitable' from the first moment that life evolved on the Earth. One can believe that biological evolution is driven by the 'fittest' and also believe that there is a tendency for the evolutionary paths to head towards complexity. However, to believe this is to believe a very different thing from believing that the heading towards complexity is a heading towards one particular form - the 'human'.
So, according to conventional wisdom the 'human' is not inevitable because the evolutionary paths that life has taken on the Earth could have been very different. You will probably have heard people assert something along the following lines: "Things could have turned out differently, if the meteor that wiped out the dinosaurs had missed the Earth then the evolution of life on Earth would have been very different; dinosaurs could still be the dominant life-force on the planet and humans would not have evolved." There is still debate about what exactly caused the end of the 'dinosaur era', but the general point is simply that biological evolution is a process which is pervaded with contingency. Life is evolving in a particular direction, then some 'freak event' such as a meteor strike radically changes that direction.
There is clearly a sense, due to these 'freak events', in which the past (and present and future) evolutionary paths which life has taken are not inevitable. The biological evolutionary paths could surely have been different. Our question is not whether biological evolutionary paths are inevitable (could not have been different), it is whether they are 'inevitable'. To say that these paths are 'inevitable' is to say that they are themselves heading in a particular direction. 'Freak events' are outside influences which can temporarily cause a deviation from the pre-existing evolutionary trajectory; however, once knocked off course, the evolutionary paths can reassemble and head back towards the direction which they were previously heading in. So, to believe in 'inevitability' is not to believe that evolutionary paths could not have been different, it is simply to believe that evolutionary paths are heading in a particular direction.
Consider an analogy. John is attempting to drive from Glasgow to London, and he is absolutely desperate to get to London. When he leaves Glasgow there is a sense in which it is 'inevitable' that he will arrive in London. This 'inevitability' does not entail that the path which John takes to get from Glasgow to London is inevitable. If things go smoothly then he will take the route he planned in advance. But he could encounter roadblocks and/or accidents ('freak events') which cause his path to be very different. Despite his desperation it is also not inevitable that he will arrive in London (the stress caused by his desperation to get to London could cause the ultimate 'freak event' - the death of John).
So, to believe that the cosmic bringing forth of the 'human' was 'inevitable' is to believe that the biological evolutionary paths of life on Earth were always heading towards the 'human'. There are many possible paths to this destination, and the destination itself was not inevitable (just 'inevitable'). Let us move from 'inevitability' and consider that which is hypothesised to be 'inevitable' - the 'human'. What is a 'human'? The answer seems to be obvious: humans are a species of animal which inhabit the Earth; they typically have two arms, two legs, a torso and a head. This is how we typically think of the 'human' as a member of a particular biological species - the 'human species'. I don't have this conception of 'human' in mind - simply a member of a biological species with a head, torso, arms and legs - when I consider whether the 'human' was 'inevitable'. I have in mind a different conception of 'human': the essence of what we call 'humans' is not their torso, arms, head and legs. The 'human' is marked out by the way it sees itself compared to its surroundings, it is marked out by the particular way that it thinks, it is marked out by its actions - such as engaging in science and developing technology.
When I say that the 'human' was 'inevitable' I don't mean that a particular biological arrangement of limbs was 'inevitable'. I mean that this way of seeing itself, this way of thinking, these 'unique' actions, were inevitable.
Was the cosmic bringing forth of humans 'inevitable'? I believe that it was. There are many reasons which lead to this conclusion and I will consider the first of them very soon.