Within linguistic semantics, it is near orthodoxy that the function of the word'if'(in most cases) is to mark restrictions on quantification. Just as in the sentence ‘Every man smokes', the common noun'man'restricts the quantifier ‘every, in the sentence “Usually, if it's winter it's cold,“it's winter acts as a restrictor on the situational quantifier ‘usually'. This view, originally due to Lewis (1975), has been greatly extended in work by Heim (1982) and, most notably, Kratzer (1978, 1981, 1986, 2012) into a rich theory of almost all uses of the word'if'. I call this the restrictor view of ‘if'. Despite its linguistic prominence, this view of the word'if'has played little role in the philosophical discussion of conditionals. Fairly recent philosophical surveys such as Bennett's (2003) book-length introduction or Edgington's (1995, 2008) review articles do not even mention the restrictor view. Stranger still, in his seminal work on conditionals and probability, Lewis (1976, 1986) does not discuss the restrictor view that he pioneered, despite the intimate relation noted by Kratzer (1978, 1986). This chapter tries to fill in the gap left by these omissions.? I make four main points. First, I argue that given the current state of affairs our best bet is to accept the ‘restrictor view'and to assume that ‘if'is not ambiguous, so that we should accept some variant of the full Heim/Kratzer account of conditionals. Second, I argue that the restrictor view is compatible with all major philosophical views of conditionals, if they are understood in the right way, namely as theories about the meaning of certain sentences that include ‘if’, rather than as theories about the meaning of the word'if'itself. Third, I argue that the …