This is like a brief history and/or future estimation of the notion of “culture”. (for my own sake, basically)
To me, history of the notion of culture seems like...
"Culture" with a CAPITAL "C"
↓ ↓ ↓ ↓
"culture" as a COUNTABLE noun (as is designed to use in a plural form)
↓ ↓ ↓ ↓
"culture" as an UNcountable noun (as an abstract noun, or a more universal "idea")
As explained in the following few paragraphs...
The term culture was once (and still is, by much less frequency,) used as a synonym for “civilization”. The notion of culture at that time was Culture with a capital “C”, for civilization was assumed to exist only in the West. (*1)
Such conception was relativised by anthropologists and other social scientists during the last two centuries. When Edward Tylor defined the term as “that complex whole which includes knowledge, belief, art, morals, law, custom, and any other capabilities and habits acquired by man as a member of society” (Sir Edward Burnett Tylor 1871), which all the inheritors of the discipline have followed until now, their assertion was that culture”s” exist all over the world, even in the most detached and primitive societies. This notion of culture, which is now used most frequently and widely in the daily lives of human beings, not to mention all fields of academic discourses, is a “countable” noun. The point of this idea is that every group of people has its own culture, and that all the cultures on earth are equally complex yet complete and integrate, and the most important of all, of equal significance. All the highly complicated features of a culture are functioning in a perfectly harmonious way, within that bounded whole of “culture”.
This cultural relativism, with the strategic use of the term as a plural noun, put itself on a par with the other theories of natural sciences such as racism and social evolutionism. (*2) However, this notion of “bounded culture” sometimes makes individuals stuck in that “supposedly” bounded entity. The truth is not that human beings are living by that strict set of “laws” within each culture, but that they are just utilizing the notion in the course of their daily lives.
To see human life more precisely, or more realistically, one should take culture to be the relationship between an individual and the surrounding social/physical situations around him. Supposing, in the course of daily lives, all humans basically and almost exclusively a) have that distinction between “self” and “other”, knowing that others around him/her have the same intentionality s/he him/herself has when s/he does many of whatever s/he does, and b) care about what other people’s intentions (and perhaps other animals’ and material objects’ “intentions”) are, estimating them by applying a narrative structure or causality to the collateral set of events; then, one can see human beings as relationship-making beings. In every moment of time they are in mind making/having/updating such estimated intentionality of the surrounding people/things. In so doing, they are imagining and/or organizing the world around him. The word “culture”, whether speaking of symbolic matters, material things, or the ways of behaviour, should refer to such “relationships” that individual human beings are consistently creating and altering.
In this sense, “culture” is much more like a universal (yet simple and basic) mechanism of human life. So, when it is necessary to distinguish this idea from the former rigid notion of “culture [C]” or culture as a countable noun, I can call this “culture [U]”, culture as an uncountable noun. It is true, fairly undeniable that people so often use the notion of culture [C], but they are not living their entire lives within and by those strict rules/laws of culture [C]. The truth is that they just occasionally and temporarily utilizing the notion for some (or perhaps no) intention in the course of daily lives. They never stay permanently in a single set of rigid rules (and indeed no one has ever done that in human history). If one is to gain the more precise perception of human life than that of the 19th and 20th century, then one has to be conscious of this notion of “culture [U]”, which is the principle of all human beings living in social relationships.
※２社会人類学が進化論生物学などと学問として肩を並べることができたのはその科学的手法（というか修辞法）によると思われる。(たとえば Michael Carrithers 1992にその分析あり)「科学的（とくにSocial Science/Hard Science/Higher Science）」に見せかけた人間に関する科学はまさに”experimental science in search of law” (Clifford Geertz 1973)だった！（にみせかけたものだった？？）
※ちなみに上のギアツの言葉は前後も載せると”Believing, with Max Weber, that man is an animal suspended in webs of significance he himself has spun, I take culture to be those webs, and the analysis of it to be therefore not an experimental science in search of law but an interpretive science in search of meaning.”なのですが、僕の考えでは、（もちろん、人間に関する現象が複雑すぎてその全てを捉える事なんて不可能に近いから分析対象となる現象を選ばなければいけない、という意味でその分析は恣意的にならざるを得ないという前提もあるのですが、）社会的動物としての人間の生き方の本質というのが上に書いたみたいに他の人たちの行動とか様々な社会的・物理的現象の因果関係を推測／想像／解釈することにあるがために、人間に関する科学の目的は、そこに実際に生きる人達が自分の周りの世界にどのような解釈を与えているのか（つまり、どのような意味を見出しているのか）ということを、その人達がするのと同じ方法で解釈することにあるべきなのです。
CARRITHERS, Michael (1992) "Why Humans Have Cultures."
GEERTZ, Clifford (1973) "The Interpretation of Cultures."
TYLOR, Edward Burnett (1871) "Primitive Societies."