Question: is there a consensus view of why we age?
About the article "Biology", section "Basic unresolved problems in biology".

Candidate passages:
Some idealists (subjective idealists) hold the view that there isn't one particular way things are, but rather that each person's personal reality is unique.
Such idealists have the world view which says that we each create our own reality, and while most people may be in general agreement (consensus) about what reality is like, they might live in a different (or nonconsensus) reality. 
Unlike standard academic disciplines, the Theory of Knowledge course uses a process of discovering and sharing students' views on ""issues"" (an umbrella term for "everything that can be approached from a TOK point of view"), so "there is no end to the valid questions that may arise", "there are many different ways to approach TOK," "the sheer scope of the TOK course is daunting" and "teachers and students need the confidence to go too far outside their traditional comfort zones."
Teachers have freedom to select a teaching methodology and course material that will convey the theoretical foundation of essential concepts, and may provide an environment in which these concepts can be discussed and debated.
The focus of the discussion should not be the differentiation between "right" and "wrong" ideas, but on the quality of justification and a balanced approach to the knowledge claim in question.
The TOK course uses a combination, in no particular order ("many entry points and sequences are possible"):  "Ways of knowing": (sense perception, reason, emotion, and language).
How do we gain knowledge of the world, and what are the advantages and disadvantages of each way in which we learn of the world and our place in it.
Starting in fall of 2013, the IB curriculum has changed to include four other ways of knowing: intuition, imagination, faith, and memory.
"Areas of knowledge" (mathematics, natural sciences, human sciences, history, the arts and ethics): their distinct natures and methods of gaining knowledge, the types of claim each makes and the issues to consider (e.g.
"How do you know that the scientific method is a valid method of gaining knowledge?
", "What is the reason for having historical knowledge, and how is it applied in life?").
Starting in fall of 2013, the IB curriculum has changed to include two more areas of knowledge: religious knowledge systems and indigenous knowledge systems.
Factors that transcend individual ways of knowing and areas of knowledge: * "Nature of knowing": what are the differences between information, data, belief, faith, opinion, knowledge and wisdom?
* "Knowledge communities": what is taken for granted in a community?
How can we decide which beliefs we ought to check further?
* "Knowers' perspective and applications of knowledge": how do age, education, culture and experience influence selection of sources and formation of knowledge claims?
If you know something, or how to do something, do you have a responsibility to use your knowledge?
* "Justifications of knowledge claims": why should claims be assessed critically?
Are logic, sensory perception, revelation, faith, memory, consensus, intuition, and self-awareness equally reliable justifications?
Use of coherence, correspondence, pragmatism, and consensus as criteria of truth.
The TOK course is expected to involve 100 teaching hours over the two years of the Diploma Programme.
Having followed the course, students should be competent to analyse knowledge claims and respond to knowledge issues in the context of different areas of knowledge and ways of knowing, expressing ideas accurately and honestly, using examples from their own experiences as learners and in outside life. 
Sunni view.
The hadith of Muhammad which states that "My "ummah" will never agree upon an error" is often cited as a proof for the validity of ijmā'.
Sunni Muslims regard ijmā' as the third fundamental source of Sharia law, just after the divine revelation of the Qur'an, and the prophetic practice known as Sunnah.
While there is differing views over who is considered a part of this consensus, the majority view is split between two possibilities: that religiously binding consensus is the consensus of the entire Muslim community, or that religiously binding consensus is just the consensus of the religiously learned.
The names of two kinds of consensus are:  "ijma al-ummah" - a whole community consensus.
"ijma al-aimmah" - a consensus by religious authorities.
Malik ibn Anas held the view that the religiously binding consensus was only the consensus of Muhammad's companions and the direct successors of those companions in the city of Medina.
According to Iraqi academic Majid Khadduri, Al-Shafi'i held the view that religiously binding consensus had to include all of the Muslim community in every part of the world, both the religiously learned and the layman.
Thus, if even one individual out of millions would hold a differing view, then consensus would not have been reached.
In an attempt to define consensus in a form which was more likely to ever occur, Al-Ghazali expanding on al-Shafi'i's definition to define consensus as including all of the Muslim community in regard to religious principles and restricting the meaning to only the religiously learned in regard to finer details.
Abu Hanifa, Ahmad bin Hanbal and Dawud al-Zahiri, on the other hand, considered this consensus to only include the companions of the prophet Muhammad, excluding all generations which followed them, in Medina and elsewhere.
Views within Sunni Islam branched off even further in later generations, with Muhammad ibn Zakariya al-Razi defining even a simple majority view as constituting consensus and Ibn Taymiyyah restricting consensus to the view of the religiously learned only.
Muhammad ibn Jarir al-Tabari's position was not entirely clear, as modern scholarship has attributed to him both the view that consensus means a simple majority, and that it means only the consensus of the companions of Muhammad. 
In his book "Crazy wisdom", the Tibetan tülku Chögyam Trungpa describes the phenomenon as a process of spiritual discovery:Instead we explore further and further and further without looking for an answer.
[...] We don't make a big point or an answer out of any one thing.
For example, we might think that because we have discovered one particular thing that is wrong with us, that must be "it", that must be the problem, that must be the answer.
No.
We don't fixate on that, we go further.
"Why is that the case?"
We look further and further.
We ask: "Why is this so?"
Why is there spirituality?
Why is there awakening?
Why is there this moment of relief?
Why is there such a thing as discovering the pleasure of spirituality?
Why, why, why?"
We go on deeper and deeper and deeper and deeper, until we reach the point where there is no answer.
[...] At that point we tend to give up hope of an answer, or of anything whatsoever, for that matter.
[...] This hopelessness is the essence of crazy wisdom.
It is hopeless, utterly hopeless. 
Rough consensus is a term used in consensus decision-making to indicate the "sense of the group" concerning a particular matter under consideration.
It has been defined as the "dominant view" of a group as determined by its chairperson.
The term was first used by the Internet Engineering Task Force (IETF) in describing its procedures for working groups (WGs).
The means to establish rough consensus was described by the IETF as follows:Working groups make decisions through a "rough consensus" process.
IETF consensus does not require that all participants agree although this is, of course, preferred.
In general, the dominant view of the working group shall prevail.
(However, "dominance" is not to be determined on the basis of volume or persistence, but rather a more general sense of agreement).
Consensus can be determined by a show of hands, humming, or any other means on which the WG agrees (by rough consensus, of course).
Note that 51% of the working group does not qualify as "rough consensus" and 99% is better than rough.
It is up to the Chair to determine if rough consensus has been reached (IETF Working Group Guidelines and Procedures).
The phrase is often extended into the saying "rough consensus and running code", to make it clear that the IETF is interested in practical, working systems that can be quickly implemented.
There is some debate as to whether running code leads to rough consensus or vice versa.