What is biconditional?

What Does biconditional Mean

If we look for the biconditional term in the dictionary of the Royal Spanish Academy ( RAE ), we will not find it. The concept, however, is used frequently in the realm of philosophy and logic .

A biconditional is a proposition that has a double conditionality , fixed by the formulas that it relates in a binary way. In colloquial language, the idea is associated with the expression "if and only if" : the biconditional is true if the terms it relates share the value of truth (that is, if the two formulas are true or if the two formulas are false ). On the other hand, when the formulas have different truth values ​​(since one is false and the other is true), the biconditional is false.

In other words, one biconditional implies that R is a condition necessary and sufficient for S . It can also be stated that "if R, then S" and that "if S, then R" .
Let us take the example of the following proposition: "A human being belongs biologically to the male gender if he has male reproductive organs . " Leaving aside cultural and identity issues, it can be said that a human being is part of the male gender "if and only if" he has male reproductive organs.
Returning to the formulas mentioned above: "If a human being belongs biologically to the male gender, then it has male reproductive organs . " This can also be expressed the other way around: "If a human being has male reproductive organs, then biologically he belongs to the male gender . " As you can see, we are dealing with a biconditional proposition : it requires that both terms have the same truth value to be true.
In addition to the "particles" or "links" that we have mentioned that are essential in the biconditional, we cannot ignore other elements that, in the same way, are used in it. We are referring, for example, to "is necessary and sufficient for" or "is equivalent to".
In the same way, we cannot ignore other really important aspects of the biconditional. We are referring, for example, to the fact that it is also used strongly within the field of mathematics. In this case, it must be stated that the symbols used to affect the aforementioned biconditional are the double-headed arrows, one in each direction.
Likewise, it must be taken into account that, with the advancement of technology, we also come across the fact that it is also important within what is known as digital logic. In this case, the biconditional operator to be used is XNOR.
In addition to what is indicated, in order to summarize certain ideas, we have to start from the fact that the biconditional proposition has what are several forms of translation, among which we can highlight the following:

-P is a necessary and sufficient condition for q.

-P yes and only yes q. An example would be: “P = A triangle is right. Q = A triangle has a right angle ", which would result in that A triangle is a right angle and only if it has a right angle".

-If p then q and reciprocally.

-Q is a necessary and sufficient condition for p.

-Q yes and only yes p.

-If q then p and reciprocally.

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