An important aspect of demonstratives is that of spatial deixis. Deixis marks the relationship of something to a point of reference, distance in the case of spatial deixis.
In English, here and there denote the spatial distance in relation to the speaker, the first proximal (near to the speaker), the second distal (far from the speaker). Likewise this/these and that/those. This is not the only possible deictic system a language can have, for example:
- the tripartite ko-, so- and a- in Japanese, indicating respectively nearness to the speaker, nearness to the interlocutor and distance from both.
- The tripartite seo, sin, siúd in Irish has proximal, medial and distal meanings (i.e. this, that near and that yonder)
- The quadripartite i- (here) e- (there nearby), a- (there that I can see), u- (there that I can't see)
French is often described in paedagogical materials as having a system similar to that of English, with ici being the proximal demonstrative adverb and là being its distal counterpart, but as you've noticed là is used much more often than ici, and in reference to both proximal and distal elements.
The truth is that while such a spatial deixis contrast used to exist in Middle French, it has weakened to the point of near-disappearance in the modern language.
Among the language of the world, Modern French is unusual in not making a spatial deictic distinction in its demonstrative adverbs. Of the 234 languages surveyed by the World Atlas of Language Structures, only 7 share this feature.
The evolution of spatial deixis in French
So how did this oddity develop?
Looking back at the history of the French language, one can remark a constant weakening of its demonstrative system.
Latin had a system similar to that of Japanese, with hic (near the speaker), iste (near the hearer) and ille (far from both).
This system collapsed to a two-way distinction in the ancestor of French, Romanian and most Italo-Romance languages, but not in every other Romance variety (cf. Spanish este, ese and aquel). Reinforced forms of the old demonstratives were used in Old French to show proximal deixis ((i)cist, from ecce iste) and distal deixis ((i)cil, from ecce ille). Those words could be used as determiners and pronouns, but not adverbs (the ancestors of ici and là, (i)ci and la, from ecce hic and illac, were used).
A new merger started with the masculine plural forms of cist and cil, which by Middle French had both evolved to cez. This prompted the creation of an analogical fused singular ce. Those words survive to Modern French as the demonstrative determiner ce(s). A new series of demonstrative pronouns was then created from ce + the tonic personal pronoun (i.e. ce+lui = celui).
This left French without a deictic distinction in either its demonstrative pronouns or its demonstrative determiners. To repair the system, the sole words that still showed a constrast -(i)ci and là- were recruited to optionally reinforce the other demonstratives:
Ce+ci/là -> ceci, cela
Cette chose+ci/là -> cette chose-ci, cette chose-là
Ce+eux+ci/là > ceux-ci, ceux-là
This completely optional reinforcement further weakened the deictic contrast in the language. As it wasn't necessary in most contexts, this left the demonstrative adverbs as abnormally marked. This anomaly was rectified by recruiting là as an unmarked, deictically neutral demonstrative adverb.
To replace là as the optional distal demonstrative adverb, the more marked là-bas was in turn recruited, bringing the adverbs in line with the rest of the demonstrative system, with a normal, unmarked form, and an optional distal/proximal contrast. (Compare to English where there is no way not to indicate if something is far or near)
Spatial Deixis in Modern French
Sadly, the change outlined above was still in progress when French was standardised, leading to a certain confusion in both ESL and native manuals and differences between registers.
The generalized tendency is for the optional deictic contrast to weaken further, with old distal forms supplanting their proximal counterparts, as exemplified by ça supplanting both ceci and its progenitor cela as an inanimate demonstrative pronoun. Likewise the enclitic demonstrative -là, tends to be being systematically preferred to -ci and voilà to voici.
To come back to your main question after this long explanation, one uses là in most situations where the distinction isn't very important. Ici and là-bas are used when there is a risk of incomprehension, or when the distinction is important. This is highly dependent on the context you find yourself in as it relies on the speaker finding a deictic distinction important enough to include in their current speech act. It's thus difficult to give a systematic rule.
As an example, take "I come from (t)here". You'd say it as:
"Je viens de là" when you're showing the place on a map (you're equally far from all positions on the map, being a bird eye view observator) or if someone just mentioned your native town in a conversation (where you are, currently, in relation to this place doesn't matter to your present conversation)
"Je viens d'ici" when you want to mention that you've grown up in the town you're currently in (being in the town is important and relevant to the conversation)
"Je viens de là-bas" when you're pointing out the direction you just came from (that you came from somewhere away from your current position is relevant)
A note on temporal deixis
Contrarily to everything I've just written about spatial deixis, temporal deixis remains strong and stable:
Ce mois-ci can only mean "this month we're in" and ce mois-là designates every other month. While it's perfectly possible to say "ce PC-là" to speak of the computer you're sitting in front of right now, it's not possible to say "cette année-là" to mean the current year. The unmarked "ce mois" is normally understood as synonymous with "ce mois-ci".
Là is also used with a temporal meaning to indicate the present instant, translatable as "right now".
This chapter on deixis in Maienborn, von Heusinger and Portner (eds.) 2012, Semantics (HSK 33.3), de Gruyter, 1–25
Holger Diessel. 2013. Distance Contrasts in Demonstratives.
In: Dryer, Matthew S. & Haspelmath, Martin (eds.)
The World Atlas of Language Structures Online.
Leipzig: Max Planck Institute for Evolutionary Anthropology.
(Available online at http://wals.info/chapter/41, Accessed on 2017-11-16.)
Frances Kane, Demonstratives in Irish, Paper given at INFL (Irish network in formal linguistics) Conference, University of Ulster (2011)
Celine Guillot, From Old French to Contempory French in Konstanze Jungbluth, Federica Da Milano (eds) "Manual of Deixis in Romance Languages", pp. 559-580