The Sapir-Whorf Hypothesis states that language is not merely a way to express ideas, but that it effects the range of ideas that we can have. For example, if there's no word or term for a particular concept in one's language(s), then it typically is hard for one even to conceive of the concept in the first place, let alone communicate that concept to another person.
- "... words don't merely match pre-existing things in the world. Rather, they shape and encapsulate ideas about things--how they are categorized (compare dog vs. canine), how we are interacting with them (compare sheep vs. mutton), how the word functions grammatically (compare the noun cow vs. the adjective bovine), and how we wish to represent our attitudes about them (compare critter vs. varmint)." 
Rebecca Ash wrote:
- "The Sapir-Whorf hypothesis theorizes that thoughts and behavior are determined (or, at least, partially influenced) by language. If true in its strongest sense, the sinister possibility of a culture controlled by Newspeak or some other language is not just science fiction. Since its inception in the 1920s and 1930s, the Sapir-Whorf hypothesis has caused controversy and spawned research in a variety of disciplines including linguistics, psychology, philosophy, anthropology, and education. To this day it has not been completely disputed or defended, but has continued to intrigue researchers around the world." 
Wilhelm von Humboldt, writing a century before Sapir wrote a strong version of linguistic determinism:
- "Man lives in the world about him principally, indeed exclusively, as language presents it to him."
Name and origin
The hypothesis is named for Edward Sapir and Benjamin Lee Whorf, supposedly deriving from the latter's observations about time words in the Hopi language.
It is a linguistic theory (also known as the "Whorfian hypothesis" and the "linguistic relativity hypothesis"). Although it is named for Sapir and Whorf, it is unclear whether either man had anything to do with its formulation. "Alford (1980) also notes that neither Sapir nor Whorf actually named any of their ideas about language and cognition the Sapir-Whorf Hypothesis. This name only appeared after their deaths." Some sources said it was named after them incorrectly. Edward Sapir studied the research of Wilhelm von Humboldt, whose own linguistic theories, published in "Über das vergleichende Sprachstudium" ("On the comparative study of languages") in 1836, focussed on a strong version of linguistic determinism, saying "Man lives in the world about him principally, indeed exclusively, as language presents it to him." Sapir took this idea and built on it to a lesser degree, clearly stating that there is clearly a connection between language and thought. The trail of influence could, however, be traced back to Franz Boaz, considered to be the founder of anthropology in the United States, and under whom Sapir was an outstanding student.
- ... observers are not led by the same physical evidence to the same picture of the universe, unless their linguistic backgrounds are similar ...
- From this fact proceeds what I have called the "linguistic relativity principle," which means, in informal terms, that users of markedly different grammars are pointed by their grammars toward different types of observations and different evaluations of externally similar acts of observation, and hence are not equivalent as observers but must arrive at somewhat different views of the world.
- "Whorf [was] appealing to the general educated audience of his day to become linguistically aware -- to realize to what extent the language you speak influences what and how you think."
- "In truth, it is widely accepted by ethnolinguists that culture affects language, but it is controversial as to whether or not language affects culture."
|“||We dissect nature along lines laid down by our native languages. The categories and types that we isolate from the world of phenomena we do not find there because they stare every observer in the face; on the contrary, the world is presented in a kaleidoscopic flux of impressions which has to be organized by our minds - and this means largely by the linguistic systems in our minds. We cut nature up, organize it into concepts, and ascribe significances as we do, largely because we are parties to an agreement to organize it in this way - an agreement that holds throughout our speech community and is codified in the patterns of our language. The agreement is, of course, an implicit and unstated one, but its terms are absolutely obligatory; we cannot talk at all except by subscribing to the organization and classification of data which the agreement decrees. (Emphasis the author's own)||”|
"Sapir believed that language shapes human perception and directs human behavior. From his view, understanding a culture was impossible without understanding the historical development of that culture’s language." An example of Sapir's beliefs can be found in George Orwell's book 1984. Here, "Newspeak" was created to alter the way people thought about the government. The new vocabulary was a method of mind control, since the population could not think of things that were not included in the vocabulary. In essence, they were prisoners of their own language.
There are two opposing theories regarding the the relationship between language and thought. These are referred to as "mould theories" and "cloak theories". Mould theories see language as a "mould", used to cast various thought categories. Cloak theories, by contrast, represent the view that language is a "cloak" that conforms to the customary thought categories of a language's speakers. However, behaviourists believe that language and thought are identical and that thinking is entirely linguistic. Non-verbal thought does not exist and there is no translation from thought to language.
The Sapir-Whorf Hypothesis is a mould theory of language and consists of two associated principles. These are "linguistic determinism", which states that our language determines our thinking, and "linguistic relativity", which states that people who speak different languages perceive and think about the world quite differently.
This hypothesis contradicts the cloak theory, which believes that language is simply the appearance of thought.
Whorf believed wholeheartedly in "linguistic determinism"; in other words, what one thinks is determined by their language and he also supported "linguistic relativity", which states that the differences in language reflect the different views of different people.
An example of this is the studies Whorf did on the Hopi language. He studied a Hopi speaker who lived in New York city near Whorf. based on the fact that Hopi speakers do not include tenses in their native tongue, he concluded that they therefore must have a different sense of time than other groups of people.
However, recently further studies of the Hopi language have revealed that although the Hopi do not include references to the past, present or future in their grammar, they do, in fact, have two other tenses, "manifested" and "becoming manifested". Manifested includes all that physically is and ever has been, which includes such things as the senses and concrete items. Becoming manifested includes anything which is not physical, has no definite origin and cannot be perceived with the senses.
Hopi verbs are always expressed within terms of these two tenses. In this way, the Hopi do include some aspect of time, but in a different way than a native English speaker would recognize. The biggest limitation of Whorf's research was that he focussed on the language of one individual, outside of his native environment, rather than studying the entire Hopi community.
Few linguists today would accept the pure form of the Sapir-Whorf hypothesis, yet may find some resonance in a more moderate take on the theory. The "pure" and "moderate" forms differ in that the pure form places the emphasis on the potential for thinking to be influenced rather than determined by language and that it is a two-way process, in other words, "the kind of language we use is also influenced by the way we see the world."
There is some middle ground to be found in moderate form of both. For example, there are languages with words for things that other languages do not have. A good example is the Neuer people of Sudan, who have more than 400 words to describe cattle. Each word indicates differences in colour, size, body shape and the shape of the horns. Just because we do not have a word with the same meaning, does not imply that we cannot comprehend what the word is - and it can be counter-argued against Sapir-Whorf that simply by being able to comprehend the word, we can indeed the see world through that speaker's eyes. 
- The Great Whorf Hypothesis Hoax
- "Benjamin Whorf," New World Encyclopedia, http://www.newworldencyclopedia.org/entry/Benjamin_Whorf?oldid=795326 (accessed February 25, 2009).
- Whorf, Benjamin; Language, Thought, and Reality: Selected Writings of Benjamin Lee Whorf (John Carroll, Editor) ; 1956; MIT Press; pp 213-14.
- "Edward Sapir," New World Encyclopedia, (accessed February 25, 2009).
- Bruner, J. S., J. S. Goodnow & G. A. Austin ( 1962): A Study of Thinking. New York: Wiley