Table 3 Isolation propositions—inference to best explanation

Hill’s aspects of association

Strength

Loneliness has strong QUAL assoc. & lack of support strong QUANT assoc. with depression

Consistency

The role of loneliness and lack of support has been found as a cause of depression has been found in large number of studies.

Specificity

No specificity identified

Temporality

No temporality demonstrated in this study

Biological gradient

Higher the lack of support the higher the observed depression

Plausibility

The association between loneliness and depression is biologically plausible

Coherence

The association is coherent with what is know

Experimental evidence

Interventions that provide support have been demonstrated to reduce depression

Analogy

There is an analogy between the effect of loss of expectation and loss of support. Both result in a similar effect

Thagard’s Principles

Symmetry

There is symmetry between lack of support causing depression and support preventing depression

Explanation

The isolation proposition a) coheres with evidence on depression, b) evidence on role of support, isolation, loss of control, and c) is a single proposition

Analogy

Isolation causing stress is coherent with isolation causing depression mediated through stress

Data priority

Proposition describes the observation re isolation, support and depression

Contradiction

There are no contradictory proposals

Competition

No competitive explanation identified where p and q were not explanatorily connected

Acceptance

The isolation proposition is coherent with the overall system of propositions

Thagard’s Criteria

Consilience

The central role of isolation as an explanation for stress and depression explains a range of facts but all known facts

Simplicity

Isolation is not sufficient to cause of depression. Not the most simple explanation

Analogy

Isolation causing stress in mothers is analogous to loss of control or expectations causing stress