Philosophy has traditionally two views concerning time, namely, the ‘static view of time’ and the ‘dynamic view of time’. The static view of time as embraced by philosophers like Parmenides and Zeno of Elea held that the appearance of temporal change is a mere illusion.
This means that events deemed ‘past’ in one frame of reference must be deemed as the ‘future’ in other frames; thus hinting that the difference between the past and the future might be just one that is subjective to experience rather than a real ontological divide. The dynamic view of time chosen by philosophers like Heraclitus and Aristotle, maintained that the future lacks the certainty of the past and the present therefore reality is continually being added to as time passes. This implies a ‘movement of time from the past into the future’ as ‘future events become present before finally receding into the past’.
Both views of time are true to a certain degree. In fact, both views seem to complement each other and produce a more complete picture of our understanding of time. More importantly, both views show us a fundamental principle in philosophy, that is; some things change and some things do not change. Coming to this point, the task of the philosopher is to determine to a certain degree of accuracy the things that change with time and the things do not.
We all know that some laws of nature and physics do not change relative to time. For example, as long as certain conditions are met, water boils at 100 degrees Celsius. If this law of physics do not hold true, no corporation would dare manufacture electrical stoves and kettles! Besides physics, other concepts and principles especially those found in mathematics are constant regardless of the flow of time. We can always with utmost certainty answer that 5 + 7 = 12 since we cannot conceive a world where the answer to such a question would be any different than the one we already know.
These unchanging laws in reality lead us to examine two kinds of propositional knowledge which philosophers call a priori and a posteriori.
Knowledge is said to be a priori when it is a necessary truth, independent of the sense-experience. The most cited example of this kind of knowledge is again mathematics because the authority and validity of mathematical knowledge do not depend upon evidence obtained through experience.
On the other hand, knowledge is said to be a posteriori when it refers to a contingent truth that is authenticated and justified only through the sense-experience. But what can we say about the concept of time? Is it a priori or a posteriori knowledge? -see full article at Eternity in an Hour