AUTHOR=Baratgin Jean , Politzer Guy , Over David E. , Takahashi Tatsuji 

TITLE=The Psychology of Uncertainty and Three-Valued Truth Tables

JOURNAL=Frontiers in Psychology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2018.01479

DOI=10.3389/fpsyg.2018.01479

ISSN=1664-1078

ABSTRACT=<p>Psychological research on people's understanding of natural language connectives has traditionally used truth table tasks, in which participants evaluate the truth or falsity of a compound sentence given the truth or falsity of its components in the framework of propositional logic. One perplexing result concerned the indicative conditional <italic>if A then C</italic> which was often evaluated as true when <italic>A</italic> and <italic>C</italic> are true, false when <italic>A</italic> is true and <italic>C</italic> is false but irrelevant“ (devoid of value) when <italic>A</italic> is false (whatever the value of <italic>C</italic>). This was called the “psychological defective table of the conditional.” Here we show that far from being anomalous the “defective” table pattern reveals a coherent semantics for the basic connectives of natural language in a trivalent framework. This was done by establishing participants' truth tables for negation, conjunction, disjunction, conditional, and biconditional, when they were presented with statements that could be certainly true, certainly false, or neither. We review systems of three-valued tables from logic, linguistics, foundations of quantum mechanics, philosophical logic, and artificial intelligence, to see whether one of these systems adequately describes people's interpretations of natural language connectives. We find that de Finetti's (<xref ref-type="bibr" rid="B30">1936/1995</xref>) three-valued system is the best approximation to participants' truth tables.</p>