4.7 Hierarchy of propositions
Propositions are mostly grouped into four categories (or levels): offence, activity, source, and sub-source. This is known as the hierarchy of propositions, since each category is generally more or less important than the others when considering the case as a whole. Categorising propositions into these levels is particularly helpful when interpreting scientific evidence since the value of this evidence heavily depends on the proposition level. Examples of competing propositions for each of these levels are shown in Table 4.1 below.
| Level | Examples |
|---|---|
| Offence | \(H_p^1\): The defendant committed murder |
| \(H_d^1\): The defendant did not commit murder | |
| \(H_p^2\): The defendant assaulted the claimant | |
| \(H_d^2\): The defendant did not assault the claimant | |
| Activity | \(H_p^3\): The defendant fired the gun |
| \(H_d^3\): The defendant did not fire the gun | |
| \(H_p^4\): The defendant kicked the claimant | |
| \(H_d^4\): The defendant was not present when the claimant was kicked | |
| Source | \(H_p^5\): The glass from the defendant’s clothing originated from the smashed window |
| \(H_d^5\): The glass from the defendant’s clothing originated from some other source | |
| \(H_p^6\): The blood on the defendant’s shoes came from the claimant | |
| \(H_d^6\): The blood on the defendant’s shoes came from someone else | |
| Sub-source | \(H_p^7\): The DNA on the claimant’s clothing came from the defendant |
| \(H_d^7\): The DNA on the claimant’s clothing came from someone else |