Kirchhoff's laws (two _h_'s in Kirchhoff) are relationships that hold, in the _quasi-static_ limit, between voltages and currents in a circuit, regardless of the nature of the elements in the circuit. Whether you have a circuit composed of resistors, capacitors and transistors, and one composed of potatoes, carrots and bananas, Kirchhoff's laws hold.

Ohm's law is a so-called _constitutive equation_, that is, a relation that specifies the behaviour of a certain circuit element; in this case, the two-terminal _linear resistor_. From the point of view of circuit theory, Ohm's law actually _defines_ the linear resistor: it is that element for which the voltage across its terminals is directly proportional to the current crossing the element, and the coefficient of proportionality is called _resistance_.

Therefore, you "deduce" or, rather, you directly calculate, determine or measure the resistance by employing its very definition, as you would do for any other quantity.