Is there a difference between からすると and からして？

Question

These two phrases seem to have very similar usage and I'm unable to determine the difference between them. The examples I have are: > 彼は服装からしてだらしない。きっと他の面も同じだろう。 > *kare ha fukusou karashite darashinai. kitto hoka no men mo onaji darou.* > 症状からすると、心臓の病気かもしれません。 > *shoujyou kara suru to, shinzou no byouki kamo shiremasen.* However, both of these phrases seem to translate to the English word "from" or "based on". I've asked a few Japanese friends about the difference, but they were unable to explain it eloquently. Is it possible to switch からすると and からして in the preceding examples? Will it still be grammatically correct. (Additionally, からして seems to have the meaning of "for a start" as in ひらがなからして読めない or "For a start, I can't even read hiragana." But this usage seems to be completely separate to the "from" or "based on" usage.)

Answer 1

ex 1.症状からすると、心臓の病気かもしれません。

からするとmeans: Judging from, considering

translated into English, From the symptoms, it may be a heat condition

ex 2.彼は服装からしてだらしない。きっと他の面も同じだろう。

First of all,からして is used in two different situations.

A. Judging from, based on (only the basis of the judgement ),or the expressions such as guessing and judgment can be made.

B. until, even (give as example of evidence(or start with a part),which which contains insignificant examples such as "the most basic, the smallest, the least likely" and conclude that others are obvious.

As you can see A situation has the same meaning as からすると Judge from, based on. So In the situation A, you can switch からして to からすると.

ex. 会議室にいるのは話し声からして、田中部長と佐藤課長でしょう。

From the voice, the people in the conference room are probably Mr. Tanaka and Mr. Sato.

You can switch からして to からすると.

会議室にいるのは話し声からすると、田中部長と佐藤課長でしょう。

ex 2.彼は服装からしてだらしない。きっと他の面も同じだろう is situation B

we don't say からすると for this situation.

Answer 2

Break it down: "because/from" "to do" "if/when"

If we're/you're going from XXX = based on what we see/for starters

彼は服装からして - If we're starting with his clothes/based on his clothes

だらしない。they're sloppy

きっと他の面も同じだろう。 Surely he's like that elsewhere in his life.

症状からすると、- If we're going off her symptoms/based on her symptoms/starting with the symptoms

心臓の病気かもしれません。it may be a heart condition.