According to JC Beall and Greg Restall, ‘A widespread assumption in contemporary
philosophy of logic is that there is one true logic, that there is one and only one correct
answer as to whether a given argument is deductively valid’. In addition, ‘To be a pluralist
about logical consequence, you need only hold that there is more than “one true logic”’
[1, p. 476].1 And finally, ‘We hold that there is more than one sense in which arguments
may be deductively valid, that these senses are equally good, and equally deserving of the
name deductive validity’. 
But what exactly is meant by saying that there is just one ‘true logic’? Or more than
one ‘true logic’? What exactly is meant by saying that there is one and only one correct
answer as to whether a given argument is valid? Or that there is more than one correct
answer? What exactly is meant by saying there is a single sense in which arguments may
be deductively valid rather than more than one sense? Without answers to these questions
we cannot yet determine whether Beall and Restall have successfully provided an
alternative to logical orthodoxy.
In section I, I shall present Beall’s and Restall’s position—Logical Pluralism. Based on
this presentation, in section II, I shall ask some important questions about the details of
their Logical Pluralism and argue that without answers to these questions we cannot yet
determine whether Logical Pluralism is viable or even what exactly Logical Pluralism is.
In section III, I shall try to determine what exactly Logical Monism is, and, as a result,
what exactly Logical Pluralism might be. In section IV, I shall compare Monism and
Pluralism on the problem of determining that a logical system gets validity wrong by
classifying invalid arguments as valid. I shall argue that without clear answers to the
questions raised in section II we are unable to determine whether Pluralism can avoid this
problem. At the same time I will suggest some answers which must be avoided, if
Pluralism is to avoid self-refutation. I shall conclude that Beall and Restall have failed to
demonstrate the truth of their Logical Pluralism, but have still produced a serious
challenge to the very foundations of logic.
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