Is this distinction of biblical "love" terminology compatible with scripture? I very frequently hear repeated that there are three Greek words (or word-groups, more precisely) that are translated into the same English word "love"; the words being ἀγάπη, φιλíα, and ἔρως. ἔρως is said to refer to sexual love, φιλíα to a non-sexual "brotherly love" that is not specific to Christians and ἀγάπη to the highest form of love that only a Christian can know.

However, I've never heard any backing for this claim and have a sneaking suspicion that this is one of those things that gets passed around pastoral circles without getting checked out. 

The problem lies, of course, when one imports the distinction into his/her exegesis and extracts a meaning that may not be present. For example, if φιλíα is used rather than ἀγάπη in a particular passage, one might conclude that less is being required.

So, my question is, are the semantic ranges of these words as rigid as is claimed, and are the definitions consistent with what is intended in scripture?
The commonly held understanding is partially correct, but overstated.  In reality, the semantic range of the words is broader.

Agape

It is true that the words ἀγαπάω (agapaó) and ἀγάπη (agapé) came to mean something like "the highest form of love," but this was primarily due later Christian usage of the term.  At the time of the New Testament's writing, the word had a broad semantic range, not all that different than the modern English word love.  A Greek-English Lexicon of the New Testament (BDAG), lists the following meanings (italics are suggested glosses; definitions [numbers] are direct quotes; usages [letters] are summaries):


  ἀγαπάω (verb)
  
  
  to have warm regard for and interest in another, cherish, have affection for, love
  
  a. by humans - toward other humans (in a variety of fashions) or toward God/Jesus as an act of special devotion
  
  b. by transcendent beings - toward ordinary humans or toward other transcendent beings
  to have high esteem for or satisfaction with something, take pleasure in
  to practice/express love, prove one's love
  
  
  ἀγάπη (noun)
  
  
  the quality of warm regard for and interest in another, esteem, affection, regard, love
  
  a. of human love - without an object (i.e. an abstract trait), toward an impersonal object, toward human beings, toward God/Jesus
  
  b. of God/Jesus - toward humans, referring to the relationship between God and Christ
  a common meal eat by early Christians in connection with their worship, for the purpose of fostering and expressing mutual affection and concern, fellowship meal, a love-feast
  


From these definitions, it should be clear that it is not a technical term reserved exclusively for "Christian love."  This can also be seen plainly by its use in Luke 6:32:


  If you love (ἀγαπᾶτε) those who love (ἀγαπῶντας) you, what benefit is that to you? For even sinners love (ἀγαπῶσιν) those who love (ἀγαπῶντας) them. (ESV)


If "sinners" are capable of this love, it cannot be something reserved to true believers.

Additionally, BDAG lists various non-Biblical usages of the verb to describe, for instance, love for fellow humans.  The noun form is rare outside of the Bible, although sufficient examples exist to show it did not generally have a special religious significance.  The reason it is rare is that it had a "colloquial flavor," which written works generally seek to avoid.  

Philos

The words φιλέω (phileó) and φίλος (philos) have a similar semantic range.  Indeed, φιλέω was the normal verb for many kinds of love in ancient times, but gradually lost ground to ἀγαπάω in most contexts.  It does not, however, normally refer to romantic love. BDAG lists the following meanings:


  φιλέω (verb)
  
  
  to have a special interest in someone or something, frequently with focus on close association, have affection for, like, consider someone a friend
  
  a. in regards to people - usually literal relatives extra-Biblically; to describe the relationship between believers in the Bible; occasionally, God's relationship to believers
  
  b. in regards to things
  
  c. informally to mean "like/love to do something"
  to kiss as a special indication of affection, kiss
  


φίλος (noun)


  
  pertaining to having a special interest in someone, beloved, dear, and actively loving, kindly disposed, devoted
  substantively, one who is on intimate terms or in close association with another, 
  
  a. friend - literally or "in a special sense" (for example, fulfilling a specific role - see John 3:29)
  
  b. woman friend (similar to the way a contemporary woman might use "girlfriends")
  


Eros and Storge

Ancient Greek has two other word sets sometimes associated the word English word love: ἐράω (eraō) / ἔρως (érōs) and στέργω (stérgō) / στοργή (storgḗ).  Neither occurs in the New Testament, so the BDAG entries are short.  (The words do appear in the Septuagint, however.) The entries in A Greek-English Lexicon (LSJ) list the following meanings:


  ἐράω (verb)
  
  
  love, property of the sexual passion; to be in love with
  without sexual reference, love warmly
  love or desire passionately
  
  
  ἔρως (noun)
  
  
  a. love, mostly of the sexual passion; love for one; generally, love of a thing; desires
  
  b. object of love or desire
  
  c. passionate joy
  the god of love
  at Nicaea, a funeral wreath
  name of the κλῆρος Ἀφροδίτης
  
  
  στέργω (verb)
  
  
  a. love, feel affection, freq. of the mutual love of parents and children; also used in similar authority-subject relationships such as ruler-people or master-dog
  
  b. less freq. of the love of husband and wife; also other near equal relationships such as siblings or friends
  
  c. seldom of sexual love
  generally, to be fond of, show affection for
  to be content or satisfied, acquiesce
  desire, entreat
  
  
  στοργή (noun)
  
  
  love, affection, esp. of parents and children
  rarely sexual love
  


As the above entries show, these words too have broad semantic ranges.

Summary

Typically the four words are described in Christian popular literature something along the lines of:


agape = Christian love
philia = brotherly love or friendship
eros = romantic or sexual love
storage = family love


These definitions are not incorrect per se, but greatly oversimplify the semantic range of all four words.  Essentially, they equate a word with its most common meaning (in Christian literature), which is not proper - neither English or Greek words can be so narrowly defined.  For example, agape does indeed typically refer to Christ-like love in the New Testament.  However, it does so not because of the lexical specificity of the word, but rather only because the New Testament authors typically use it that way.  

To directly address the heart of the question - no, one cannot draw exegetical conclusions from word choice alone.  It provides a clue, of course, but context is far word important in determining what the author meant in a specific Bible verse than word choice.  The dictionary definition of use of ἀγαπάω/ἀγάπη and φιλέω/φίλος have considerable overlap.

The Greeks did not have four words to describe four different kinds of love.  They had four words for one set of complex human emotion with different connotations, just like English has many (overlapping) words that describe aspects of "love".