“Big History is an emerging academic discipline which examines history from the Big Bang to the present. It examines long time frames using a multidisciplinary approach based on combining numerous disciplines from science and the humanities, and explores human existence in the context of this bigger picture.” Wikipedia.
When seen through the framework of Big History we can define our various domains of study as Thresholds. We can consider that in some measure each Threshold requires “Goldilocks” conditions where the context and constituents of an environment are “just right” for the spontaneous emergence of fundamentally new and novel forms of self-organising complexity.
If we look back at the conditions which generate the emergence of any specific Threshold we may interpret those Goldilocks conditions as predetermining the conditions which allow for a new form of complexity which emerges at that historical moment. Looking back retrospectively to claim that the emergent properties of a specific system at a specific time are an inevitability is a little like looking back at a map that we have been drawing as we are travelling through unknown terrain — of course any significant geographical features will appear in retrospect to have been inevitable as, having now been recorded in the map, they clearly come into (intelligible) existence at the moment of being recorded.
Looking back at the history of the Universe in this way and from the privileged viewpoint we possess (i.e. we exist and have the technical and intellectual capacity required to know the conditions required for us to do so), we might presume that our own arrival on the cosmic stage is a self-evident inevitability. The belief that our own existence in the Universe is in some sense probable or even inevitable is known as the Anthropic Principle. The Anthropic Principle comes in two flavours: weak and strong.
Definition of Anthropic Principle
a) : conditions that are observed in the universe must allow the observer to exist — called also weak anthropic principle
b) : the universe must have properties that make inevitable the existence of intelligent life — called also strong anthropic principle
In the context of Big History, we are examining a historical thread-of-pearls measured by a sequence of Thresholds which culminate in the arrival of sentient creatures who develop the scientific wherewithal to look back into the conditions of their origins. The very specific series of events, coincidences, emergent properties, parameters of natural laws and any number of contributing factors seem to form a vast tapestry of directed probability towards our existence.
The weak anthropic principle is a reflection on the fact that if things were otherwise than they are or if the multitudinous coincidences had followed anything but the specific causal path that they have, we would not be here to observe it — that the “(…) observed values of all physical and cosmological quantities are not equally probable but they take on values restricted by the requirement that there exist sites where (…) life can evolve and by the requirement that the Universe be old enough for it to have already done so.” [Source.] Otherwise said: the Universe has conditions that allow you to exist and this is why you do exist.
The strong anthropic principle is much more ambitious: “The Universe must have those properties which allow life to develop within it at some stage in its history.” [Source.] This is to say that the parameters and tendencies written into matter and energy and expressed through the laws of physics must inevitably result in the existence of life and this is why you exist.
In regards to the Thresholds of Big History, the weak anthropic principle characterises our existence as being a kind of “happy coincidence” and convergence of probabilities over vast time scales. The strong anthropic principle states that our existence (or something or someone similar to us) is an inevitability. There are different interpretations of the strong anthropic principle, see this link.
If Goldilocks conditions are required for a Threshold or a causal sequence of Thresholds to occur, I think that we are more likely experiencing a weak anthropic principle — that we are the results of a fortunate sequence of random accidents that have blindly led to our existence. That the parameters of physical reality are apparently finely-tuned [see recommended text “Universes”, below] to what is necessary (i.e. Goldilocks conditions) for any number of Thresholds to have just randomly fallen out of history is a fact which we can never be in a position to affirm as a process that has been in any sense directed or inevitable. From within the system of the Universe we can probably never successfully prove any statements which require a “meta-” or external, Archimedean viewpoint to justify.
In the light of the pure naked fact of our existence in the Universe, it may not ultimately matter which anthropic principle we choose to believe in. The consequences lie in the reflection that a weak anthropic principle supports more of a daisy-chain of entirely random and coincidental events which allow for the arrival of fertile Goldilocks conditions and their subsequent (and retrospectively fortuitous) Thresholds. The strong anthropic principle states that the arrival of sentience is inevitable. Probable or inevitable, which bowl of porridge do you choose ?
The Cosmological Anthropic Principle, John D. Barrow, Frank J. Tipler, John A. Wheeler, Oxford University Press, 1988 – link.
Universes, John Leslie, Routledge, 1989 – link.