What are Presumptions in Statutory Interpretation?

The first question is, what are presumptions?
Presumptions are the basic ‘expectations’ with respect to the legislative intent and the operation of statutes.
In simple words, presumptions are some expectations - based on common sense and fairness and the principles of natural justice.
These expectations are used in every step of the interpretation of statutes.
For example, if a statute is clear and unambiguous, there is no need for interpretation - it should be implemented or enforced as is.
If there is a need for interpretation, the primary principles are applied first - such as the literal rule, the golden rule etc.
If required, the secondary principles are applied next, to fine-tune the interpretation that was done through the primary rule.
The secondary rules are all those Latin phrases we discussed - such as Reddendo Singula Singulis, Ejusdem Generis.
Here, the presumptions are applied at every step of the interpretation process.
For example, the presumption of constitutionality - which is the presumption that the legislature would not have intentionally created statutes to violate the constitution.
If a statute, as per its literal text, appears to violate the constitution, then interpretation is required.
When the primary principles are applied and there are two or more possible interpretations - then the versions which violate the constitution should be discarded.
Same with secondary principles - after applying these principles if there are multiple possible interpretations - then any version which appears to violate the constitution should be ignored.
Even while implementing or enforcing the statute, if there is any violation of the constitution - then go back to step one and reinterpret again.
As I mentioned, these presumptions are based on common-sense and basic legal principles - because the constitution is the highest rule book of the country - it is common sense and a basic legal principle that the legislature can make laws within the power granted by the constitution and not violate the constitution itself.