The law of detachment (or modus ponens, or affirming the antecedent) is a logical deduction of the following form:

You have a conditional statement `p->q` (p implies q or if p then q); then you are told that the hypothesis of the conditional (p) is true; then you can conclude that the conclusion of the conditional (q) is true.

For the given statements the conditional is: I will always go outside if the weather is nice. This can be put into the form `p->q` or if p then q: If the weather is nice, then I will go outside.

Then we are given the fact that it will be sunny (nice) on Tuesday. Thus the hypothesis is affirmed for Tuesday.

**The answer is true. We can draw the conclusion that I will go outside on Tuesday.**

Of course, you must be careful when transferring a logical argument from a conventional statement. It could be argued that sunny does not necessarily imply "nice" (as it could be sunny and -40 degrees outside.)

**Further Reading**

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