Best reconstruction of the roofed space 

The last stage of the process concerns the selection of the best explanation at the present stage of knowledge from the pool of available candidates. For this purpose, this study has assessed the accounts against the seven virtues.

Generality: both accounts seem to comply with the requirement to explain a wide array of phenomena not contradicted by others. A1 can explain a broader range of observations. This would also impact the empirical breadth.

Modesty: A1 will also be the account displaying more modesty by ‘keeping the assumptions down’ (Quine and Ullian 1978: 40). It is obvious that at the present stage of knowledge A2 would require more assumptions to justify the presence of a partially roofed space. In this respect, uncertainties concerning the collection of water (sloping of the floor towards the impluvium and the absence of dripping lines) or the use of the space as a mere transitional area or strongly dependent on the season would argue against this account. Similarly, the argument that two different large-scale building programs would have both discarded the possibilities offered by a roofed-over space to convey a message about the owner’s prestige would require a certain number of assumptions.

Refutability: A1 and A2 equally possess refutability, being both falsifiable (for example imagining future evidence contradicting one theory or the other). According to Quine and Ullian (1978), the degree of refutability is measured by ‘how dearly we cherish the previous beliefs that would have to be sacrificed to save the hypothesis. The greater the sacrifice, the more refutable the hypothesis’ (1978: 48). Therefore, refutability would depend on the current state of research, or ‘the network of currently accepted propositions’ (Gawronski and Bodenhausen 2015: 14–15) concerning the roofing of a Roman house. This would place a higher degree of falsifiability on the account that a prestigious house had a roof of the type of an atrium tuscanicum (A1), rather than being completely unroofed (A2).

Conservatism: A2 appears to be the less conservative of the accounts, since ‘in order to explain the happenings that we are inventing it to explain, the hypothesis may have to conflict with some of our previous beliefs; but the fewer the better’ (Quine and Ullian 1978: 40).

Simplicity (or Occam’s razor): this would also identify A1 as the simpler of the two accounts, in that ‘the longer the leap […] the more and wilder ways of going wrong’ (Quine and Ullian 1978: 41).

Multiplicity of foils: according to Fogelin (2007: 620) ‘an explanation that can account for both where and when a particular event occurred is usually better than an explanation that only accounts for when a particular event occurred’. This virtue will again see account A1 as preferable, insofar as it can address more layers (e.g. why the individual solution was chosen – prestige – and when – the time when the house received its late second-style decoration).

Considering what has been examined, the solution best explaining the information at our disposal would be the one suggesting that the front hall, previously unroofed, would have been covered with a roof of the type of the atrium tuscanicum when the house also received its second-style decoration. The present study with its illustrated chain of reasons would identify the best explanation at the present state of knowledge, leaving space for new arguments if/when further typologies of information enter the picture.

Therefore, a 3D reconstruction has been selected as the final product of the detailed analytical process using the described IBE-based workflow. This model should not be considered a mere illustration of the final interpretation chosen as the one best explaining the different records. The process of the 3D reconstruction has a fluid relationship with the chain of reasoning during the entire process, as a means of refinement of the different hypotheses concerning the inquiry. In this context, Cameron Shelley (1996) has highlighted the importance of spatial reasoning—or visual abduction—in archaeology and anthropology. An example of how the 3D reconstruction process itself can influence the refinement of hypotheses is the question of how to cover irregular areas. The examples in the literature usually deal with very regular plots and are mostly represented in two dimensions. The very act of 28 reconstructing in three dimensions the structure of the roof allowed investigations into the feasibility of the proposed solution (position, dimension, and pitch of the different roofs). In addition, by visually inspecting the 3D model it has been possible to appreciate the differences in spatial terms of the proposed solutions helping the process of validation (e.g., appreciation of the decorative program based on the distance.

Once built, the 3D model can contribute to fostering the generation of new data. These may derive from the visual inspection of the model itself, or specific typologies of 3D investigations (for example the analysis of the contribution of natural and artificial light, Campanaro in press.; or the measurement of human visual attention within the virtually reconstructed space of the house, Campanaro and Landeschi 2022).