I've been working on related topics in Hebrew.
Tense locates a situation in time, relative to the moment of speaking
Taxis locates a situation in time, relative to a reference point about which the situation is predicated
Aspect (viewpoint aspect, to be precise) conveys the speaker’s view of the internal temporal constituency of a situation (as a single whole, or in its sub-phases and internal structure
To visualize these, I find the event model that Hans Reichenbach first proposed (Reichenbach 1947) helpful.
In this Event Model, a predication has three time frames, and verbs are inflected based on the relationship between these three times. There is the time of the utterance (called the “speech time”), the time about which the utterance is predicated (called the “reference time”), and the time the event or situation takes place (called the “event time”). Reichenbach depicted this “three-place structure of time determination” on a time line using the initials S, R, and E (for speech, reference, and event). To illustrate how this event model works, if I say now “At noon yesterday I had already eaten,” the speech time (S) is today, the reference time (R) is noon yesterday, and the event time (E), is the eating, which must have occurred some time prior to noon yesterday.
Reichenbach also incorporated aspect into his event model by allowing the possibility that the event could occur not just at one point in time, but over a “stretch” of time.
The possible tenses are determined by the relative ordering of these three time points. In the next chart labelled “TAM and the Event Model”, the “less than” and “greater than” symbols indicate temporal sequence (S is less than R means S occurs before R), and the “equals” symbol indicates simultaneity. S “equals” R means the reference point is at the same time as the time of speaking.
Tense: temporal relation between the moment of speech (S) and the moment of the event (E). E<S = “past”; E=S = “present”; E>S = “future”
Taxis: temporal relation between the event (E) and the reference time (R) E<R = “relative past”; E=R = “relative present”; E>R = “relative future”
(Viewpoint) Aspect:Overlap relation of the event (E) and the reference time (R) E within R = “perfective”; E overlapping R = “imperfective”;
Tense (sometimes called “absolute tense”) is simply the temporal relation between the moment of speech (S) and the time of the event (E). If E precedes S, the tense is past; if E follows S, the tense is future; and if E and S coincide, the tense is present.
Taxis (sometimes called “relative tense”) relates the time of the event (E) not to speech time (S), but to the reference time (R). Again, there are three temporal relations possible between E and R; these are anterior (relative past), contemporaneous (or relative present), and posterior (or relative future).
Viewpoint aspect, like tense, is concerned with time, but whereas tense is concerned with ordering the time of the situation relative to another time-frame, aspect is concerned with the temporal constituency of the situation. In Bernard Comrie’s words, “One could state the difference as one between situation-internal time (aspect) and situation-external time (tense)” (Comrie 1985, 5). The difference between “I did” and “I was doing” is a difference of aspect. The basic polarity is between depicting an event as complete or in progress. The “perfective” aspect presents the situation “as a single unanalysable whole,” and “imperfective looks at the situation from inside.” Comrie uses the following example: John read that book yesterday; while he was reading it, the postman came.
In this sentence, the same event (reading the book) is presented using two temporal constituencies: first as a complete event, then as an ongoing event. Comrie’s example implies that if the Reference Time encompasses the Event Time, the aspect is perfective, and if the Reference Time is encompassed by the Event Time, the aspect is imperfective. Robert Binnick makes this understanding of aspect explicit. He says, “Aspect has to do with the relationship of the event time E to the reference time R; complexive (perfective) aspect has E within R, imperfective has E and R overlapping, and perfect has E preceding R” (1991, 458).
Situation aspect also goes by the label “lexical aspect.” Notarius provides the most detailed breakdown of the possible situation types: Eventualities, General statives, and Abstract entities. Situations that involve change (achievements, accomplishments, and activities) are a type of eventuality called “Events” in the typology Notarius describes. The other type of eventuality is State. Along with General statives (kind-generalizations and generalizing sentences) and Abstract entities (expressing facts as objects of knowledge and propositions as objects of belief), State eventualities do not involve change.
Phasal aspect is largely encoded by this system as well, since it expresses which part of the event is in focus (comparable to where R overlaps E): at the Onset (for inchoative or inceptive expressions), Nucleus (for iterative, habitual, continuative, or resumptive) or Coda (cessative or completive) of the event.
Binnick, R. I. Time and the Verb: A Guide to Tense and Aspect. Oxford University Press, USA, 1991.
Notarius, Tania. The Verb in Archaic Biblical Poetry a Discursive, Typological, and Historical Investigation of the Tense System. Leiden: Brill, 2013.
Reichenbach, Hans. Elements of Symbolic Logic. New York: Collier-Macmillan, 1947.
Smith, Carlota S. The Parameter of Aspect. Boston: Kluwer, 1991.
Ken M. Penner
St. Francis Xavier University