Logical Impressionism

For people acquainted with logic and logicians, it comes as a surprise that Logic in the Wild is not a matter of formal or mathematical logic. It is rather a matter of coherence preservation in complex and potentially combinatorially dense contexts in either natural or specialised language. A combinatorially dense context is one with a lot of information, relations, and possible permutations. This applies to all types of languages equally, whether everyday discourse or those used in scientific contexts and more broadly in academia. In such contexts, the best we can hope for is that we can develop and deploy coherence probes—sense detectors, as it were. Actually, what we likely detect most is non-sense, failures to cohere or follow from previous propositional content. Coherence detectors are more like Geiger counters that start buzzing even with a trace of radioactivity. Logic is very sensitive to incoherence.

Often in these complex contexts—imagine, for example, the theory of evolution—we try to replicate the forms of logical validity that form the subject of formal logical study. But just as often, we do not. We practice something I would like to call ‘logical impressionism.’ Logical impressionism looks like rhetoric and shares with it a goal to persuade. It differs from it, however, in the role it gives the provision of reasons to accept the hypothesis. It is impressionistic because this cooperative exchange of reasons does not take the form of a valid argument to the hypothesis. Nonetheless, the process of reason-giving sketches various potentially critical locations in theory formation and persuasive leverage where an argument could play a role. Sometimes, the impressionistic formulation is more appropriate than a full-blown logical argument, especially as complexity rises.

Reason exchange in a cooperative context involves the principle of charity, which amounts to treating others as intelligent beings. Characteristically, it starts with establishing common ground, a ‘we’ of shared belief that serves as a stepping-off point in the mutual project of extending or shifting our shared beliefs towards those that are not at the point of negotiation shared.

Logical impressionism is bounded on one side by rhetoric and on the other by a formal mathematisation and interpretation of a theory. Rhetoric seeks to persuade without cooperation, and a mathematised theory seeks to meet the often too onerous criterion of demonstrable validity. Logical impressionism occupies a middle ground of narrative construction where reasons form the joints of a story about the way things might be. This narrative structure might take the place of a convincing narration within a speech or be formalised as a formal derivation from premises to a hypothesis as conclusion.

Logical impressionism differs from abductive reasoning (aka non-deductive reasoning, or reasoning with a margin of error), though it is approximated by it. They share the openness to non-monotonic and non-deductive logics, but impressionism adds to it the cooperative elements. One is abducted at; we are impressionistically persuaded. In the absence of cooperative endeavours of which impressionistic reasoning is one, we tend to default to pseudo reason-warring camps. Scholarship is shot through with these camps and cults.

If there is such a thing as logical impressionism, then we are confronted with a neglected field of study: namely, impressionism itself. What are the dynamics of a reason-trading cooperation? Can such an economy be formally characterised? To what purpose? Are there heuristics involved? What are they?

Written by Padriac Amato Tahua O'Leary