What are the strengths and weaknesses of kantian ethics?

Answer

Immanuel Kant favoured a categorical deontological ethic where "one ought to do thus and thus." Duties are duties regardless of the consequences. Only what is neither good nor evil in itself, but dependent on something else for its goodness or evil be called evil at one time and good at another. Intrinsically good actions are not like this; they are always good in and of themselves. Telling the truth is an intrinsic good and a lie is an intrinsic evil, that there can never be a good lie. A strength of this approach is that one need never wonder what is the correct course of action in a complex situation.

It is unrealistic to assume that moral obligations never conflict, but Kant acknowledged that even one exception to a rule proves the rule is not genuinely universal. By their own definition, an absolute rule has no exceptions, and yet there are many ways the proponents of unqualified absolutism have qualified their view or made exceptions to it.

A weakness with all forms of Unqualified Absolutism, such as that espoused by Kant, is there is no flexibility to commit a minor wrong to prevent a great wrong. As there si never a "good lie", one can not spare a dying grandmother further suffering by lying about her condition, nor can one prevent a serious crime by lying in order to confuse the intending perpetrators.